Modulators are bloody expensive new, like £2 to £3k, so that would be the reason for doing it.
There are different types as well. I am not even sure if you can buy new modulators now. Could have been on the dealers shelf for 20 years.
I got a few used modulators that have popped up on Ebay just in case. Along with Wabco controllers which sometimes go and used booster pumps.

An old post but here is an updated link to a guy on Ebay selling a service kit to repair the button Service Kit
Spring is stainless steel so should solve the corrosion problem.

I have had good experience with Auto Silicone Hoses for coolant hoses and turbo hose; available direct or on Amazon/ Ebay.
I don't have any vacuum pipes and not tried on fuel. Silicone pipes are no good for the diesel injector bleed off pipes.

The Faultmate is the most capable diagnostic system on the market for the p38. I can't compare it to the nanocom as I don't have one. The main difference is module SM035 which allows you to unlock and change all the settings in the BeCM. You can clone another used BECM. There are actually two versions of the Faultmate, one with and one without a screen. The version with the screen can be run in standalone mode but it does more when connected to a pc. There can't be many people in SA with SM035, so if you did offer it as a service there would be a slow payback on your outlay.
From what I have seen of the Nanocom, the graphics are better and it is a nice neat unit to carry around. As I remember, it was someone elses design originally and it was sold to BBS, who then added more capability to it. More software modules.
I upgraded the software on my Faultmate and paid the difference. I later added SM035. I use my Faultmate with an old Toughbook on Win 2000.
BBS also used to have an annual Christmas sale with 10% off, which I took advantage of.

Addendum: If you just wish to swap engine ECU's around, each of which will have its own unique security code, won't a Sync-Mate do this job?
Sync-Mate only 96 euros. You shouldn't pay VAT.

They gave me full credit for the single VIN software package that I had paid for previously (MP015), but not the hardware part as that is the same, against the multi vehicle full monty price (MP112). I paid the difference.
They are very restrictive though. Before I did that I bought a second Faultmate on UK Ebay. It was s/h with just two modules on it. Multi vehicle engine ECU's and BECM's only. I registered it with them and thought I would transfer the modules across to my original Faultmate. They refused to issue the codes however. You can't transfer software modules from one Faultmate to another.
I ended up selling the second Faultmate @ half price to a guy in Zimbabwe (we still keep in touch but he ran into the back of a sugar cane truck a while back due to the dust clouds and wrote his p38 off).
I ended up forking out for the full monty version. I am not sure whether they will give you credit for the gearbox module you have.
As you found out the single VIN version scans the ECU's which are connected to the car (not sure how exactly) and it is then locked to that car. If you change an ECU it won't automatically read it. You have to get their permission and get them to issue new software codes.

Thanks for the advice Clive. I will turn the regulator down as you suggest. I also wear a mask and goggles.

For very small parts, I have got an ultrasonic bath that I can use with either warm water/detergent or isopropyl alcohol (IPA). It works very well but only for small bits and pieces. Anything larger goes in the dishwasher when she is out. I set it on intense. After the cycle I put another tablet in the empty machine to make sure it is clean. She is then none the wiser. Valve blocks and brake parts mainly. Nothing big.

During the lockdown I revamped the air compressor in my workshop. It is a Wolf twin cylinder 14 cfm with a 3 hp motor on it. I have just upped the pressure to 150psi and fitted a new retractable air hose. I have got a blast cabinet and I have previously messed about with silica sand, glass beads and and even baking soda blasting. I do it out in the garden. The blast cabinet is portable and goes on top of a B&D workmate. The air system wasn't up it, but now I have rejigged it, I am planning to use it again. The ceramic nozzles seem to wear out fast as well.

I don't use Gunk or other engine degreasers as there is nowhere for the water to run off. I have to do it out in the drive. I generally use rubber gloves and a piece of terry towel soaked in petrol for wiping oil stains off the underneath of the car.

Only other thing to add is I subscribe to a few YouTube channels and one guy recommended G101 detergent for cleaning parts. I bought a 5L container but have hesitated so far to use it on aluminium parts. It is strongly alkaline.

I assume the software in your Faultmate is locked to a single VIN?
P38 parts do fail and BBS allow you to change components on the car under certain circumstances, as long as you are not doing it every 5 minutes. If you have a word with them they can issue new codes for the Faultmate. There may be a small charge. You are stuck with one ECU though.
If you want to be able to swap ECU's backwards and forwards, to check out maps for instance, you will have to upgrade to the engine ECU software module that can do all cars. They may give you a credit for the what you have already paid.
I upgraded from single VIN to the full monty able to do all p38's inc SM035 and I just paid the difference, which was still a lot.

I have got a phev that I charge at home on a cheap night time rate. If they put an extra charge on kWh from charge points it wouldn't affect me. I seldom use them, they are too expensive. Some cost more than running on diesel.
Can't see how they could monitor mileage either. Split between battery and diesel mileage is not easy to separate out.
Hmm. More questions than answers.

It raises more questions than it answers, but it has now been out for written submissions by "interested parties" so could be introduced in the October budget. A black box tracker for everyone? I don't think so, too many cars on the road, but maybe a new car requirement? I am guessing.
Using MOT recorded mileage is problematic as davew pointed out (cynically ha ha).
However, they are not going to get the revenue and the books have got to balance.
People now working from home more, coupled with a switch to hybrids.
My guess is it is going to be transferred to fuel duty, but how to tax electric cars?

The reflective coating rubs off very easily if you try and clean it. It is a couple of thou thick.

This has been on and off for a while but seems to be back in favour again. There is a House of Commons select committee looking at it and it could be introduced "within weeks" apparently.
I have just had my p38 MOT'd and the mileage I did from the previous MOT in 2020 was only 350 miles. Admittedly it was SORN'd for 5 months.
I quite fancy getting a second p38, maybe a decent petrol one and just leave it parked out in the road to be used now and then. If it is not used, it costs nothing.
I hope the new scheme is not going to be half and half. A fixed charge and a mileage charge. I have got a shed full of spares I have collected over the years to run a second, even a third.

Advantages would be cheaper more readily available parts, a simpler or more conventional braking system and easier to fix if you are in the sticks.

Disadvantages would be no traction control, no ABS, possibly less power from the brakes? ... vacuum servo vs high pressure pump.
Front to rear braking split could be solved with an adjustable valve.

I have got an Allisport radiator on my diesel that looks identical to the Direnza. We have had this discussion before me thinks.
You can weld up the old one so I wouldn't throw it out. My fan caught on the fins causing a leak and I bought an aluminium welding kit and repaired it. It. Although it is called a welding kit it was really a brazing kit that looked like silver solder. You need a gas torch with a fine point. Secret seemed to be the stainless steel fine wire brush that got the aluminium oxide layer off and the special flux.
Your leak seems to be on the weld of the header box which would be easier to weld I think. Has it split? Maybe under tension? Bolts didn't line up properly which is very often the case and caused tension?
Mine also has the engine oil cooler built in but unconnected. I was toying with the idea of using it as the auto gearbox cooler.

Fitted a non return valve in the fuel line from the tank to the filter to aid starting.
When the car has been standing for a bit, which is more the norm now, the diesel runs back to the tank and it needs an age to crank it to get the fuel through. It helps that I have got a new Hankook 1000 CCA battery.
I fitted a new in tank pump a while back and I didn't realise it didn't have a non return valve. Must have been for a petrol car. Diesel's should have a non return valve built into the pump. Car starts first thing on the key now, after preheat of course.

Scepticism from me Dave, not cynicism.

Put the car in for an MOT. It got through, but with a couple of advisories ..... ugh. Said a couple of rubber boots on the track rod were split, also handbrake was a bit high (caused by the garage who swopped my transfer box a while back).
Revised the 3d printer designs for the carpet clips. Need to print a few out now for testing. I think I need a stronger plastic like carbon fibre.
Made a jig to fit the BeCM logic board to make it easier to make connections instead of soldering onto the board.
I may be offering an unlocking and/or a cloning service. Or maybe just a backup of the settings, if there is any interest.

First I have heard of it. I can't imagine what chemical reaction takes place between hydrogen gas and solid carbon if any. Carbon is pretty inert. It will react with strong alkalis like caustic soda.
It says hydrogen gas acts as a natural solvent on carbon, so maybe they are claiming a physical interaction. But how can a gas be a solvent? It has to be a liquid in contact with the carbon. Are they using liquid hydrogen? I don't think so.
I have heard of seafoam that you can get in the states to clean out an engine. Just squirt it into the inlet with the engine running I think. It is strongly alkaline. I would only try it on my lawnmower.

I don't think Hawkeye are supported any more.

My god that's good service. We should all have you on speed dial ...... "dial-a-mod" or put in a bat phone?