My 760 had a simular problem with all the power windows, would go down like wild fire but would always stay down when cold or wet, of course. I read in the faq's how to fix the problem. I would presume the problem is caused by the same condition. When removed the switches were carbon coated from arcing. I used superfine sandpaper, I believe 1000 grit. I got it from an old kit I have for finishing model cars. I carefully cleaned the contacts and now they work like new.

I have not had to deal with the dash much so removing the trim is something I don't know yet.

Hope this helps.