I've watched the Rimmer Bros video and it all looks feasible for a 12 fingered, shovel handed ape like myself.
As I understand it, I get the EAS up to wading mode (that'll take a while!) and then jack the body up a bit to get stands underneath. I've only got the standard Jack, but four decent stands.
The axle should be... not quite hanging loose? I'm guessing that you can't really have it hanging down all the way or I won't get the springs in.
Thanks in advance!

Well, I've undone the air lines and got 2 clips out!
Neither bag will come out, one because it still has one and a half clips holding it in and the other because it just doesn't want to.
This is fun!

One of the first jobs I had to do on the P38 was rear bags.
I had no problem with the bottom, but the top of the bags, with clips removed were stuck solid. I had to give up for the day and buy a bigger pry bar! With a good soak of WD40 and a decent size pry bar, I managed to release them. Once out, fitting the new ones is very quick.

I’m pretty sure I had to cut at least one of mine in half. This allowed me to get something meaty like vice grips/mole grips on to the bottom section (where the issue was).

I think they were more or less just bonded in by the rust on the axle mount, and not at all as easy as I expected given that I was removing a plastic part that’s just held in place by wire clips. On one of my fronts, I had to get a hacksaw blade in between the bag and the axle mount and cut off the lug.

Are you stuck top or bottom? If it’s bottom, can you get some sort of drift or bar onto the D section that fits into the axle and “tap” it upwards. When I say ‘tap’…..

The bag with no clips is stuck at the top. I have pry bars (thanks Marty for the suggestion!) - I'm just struggling on where to pry it! It's like trying to lever a blancmange!
The other side isn't giving up the clips. I've only started on the bottom one which is now largely straight but the important bit is still in the hole.
I've packed up for today, I'll get more vicious with it tommorow. I had an optician's appointment in York and on the way back I picked up the male-male hose connector I was missing so now I can jetwash the whole area and get rid of all the crap. I was just using a brush today and there was a lot of mud getting in the way.
The WD40 has been liberally applied for an overnight soak :D

btw, there's an hilarious video on youtube on how to remove rear airbags. It's by an Aussie who pulls the clips out with a bent coathanger wire and the bags pop right out. I'm jealous of places that don't have rust :P

You need to get the pry bar in at the top in the gap between the body and chassis so it sits on top of the airspring and lever it downwards. If it still won't shift and you have the new springs ready to go in, then get brutal with it. Take a 1" wood chisel, slide it into the gap between body and chassis so it sits against the top part of the spring that protrudes above the chassis mounting it is stuck in as close to the chassis plate as possible. Give it a good clout with a lump hammer and you will cut the top off the airspring and the rest of it will fall out.

I'm guessing option 2 then. I've tried prying the top of the spring (where the clip goes through) and nothing doing. Still, it's a good excuse for a hearty breakfast before re-joining battle :D

Yeah, the last couple of times I've done them Unless they pull straight out, I go straight to option 2. Takes seconds and makes the job so easy.

They're out! At last.
Turns out that if you get angry enough you don't even need to remove the clips

which is just as well as the ones on the driver's side were not moving for anything.

The wood chisel was a welcome addition to the armoury, thank you Richard. It wasn't quite long enough to get all the top off the spring but it did enough damage for the top clip to no longer hold the plastic in place once I rotated the spring a bit.

I nearly took the drivers side shock out, because I couldn't get any leverage when pulling towards it. I'm confused as to why the clip was put in that way round but if it can go the other way I'll do that on re-assembly. If I bother with clips that is, they're clearly just designed to hold the bags until they rust into place properly.

Now tea :D

The new ones have been slathered in WD40 silicon version "Safe on metal, rubber and plastic" so maybe they'll come out easier. Maybe.