Power window stopping mechanism
 

Not an MB question -- my BMW 325i driver door window rolls up fine but whatever little switch that tells it it's all the way up is not working -- it just makes an obnoxious clicking noise when it reaches the top, as if the motor is still trying to roll it up but it runs out of gear, or it pops in and out of gear as there is nowhere else for the window to keep rising.

I haven't opened it up yet -- it's not that big a deal, I just watch it when I roll it up and let off the trigger right as it reaches the top. But in a couple of weeks, I'm going to do a Craigslist carpool up to WA state and I don't want my rider/drivers thinking they're damaging my car, freaking out, or thinking that my car's a borderline junker.

Anybody dealt with it before?