I haven't found a replacement, no - but I have sucessfully de-soldered them and opened the switch up and cleaned the contacts internally and got them working again.
However, if all of them don't work, then check the PCB in the overhead light unit - I've seen it before where they've had moisture drip down (possibly just from condensation even off the metal roof) and over time corroded one or more of the tracks away on the board. I've repaired a few by bypassing the affected area by soldering a new jumper wire on.
Marty
'06 4.2 Supercharged Black/Cream "Jess" -- Bought April 2021 (NZ)
'01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
'99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
'95 4.6 HSE Epsom Green/Tan -- Traded June 2008