Hello,paulgold said:
I had much trouble with window switches (intermittent working) on my 124 but that's all sorted (so far!) now. The solution? ...
Remove the switches and carefully prise the tops off. Buy a good quality contact cleaner/lubricant (ElectroLube?) from an electronics shop. Spray the contacts a few times and, if you can, clean off any more difficult deposits.
Spray again, reassemble and, with luck, you're in for a few years' operation.
On all my MBs since 1977 I have only once changed window switches and that's because my son and his friend decided to look out of the sun roof destroyed one by standing on it.
Bonne chance.
RayH