I'll be watching this because I have a similar problem. From what I understand (and I'm coming from a poorly researched point of view) the wiring between the window and the fuse box can be totally fine like mine and it may still not work as the silk-screened lines become more resistant to the flow of electricity as they get older. Mine used to work reasonably well and now barely at all.

I was hoping some local vandals would shoot it out and have my insurance cover a new one. True story, they figured if they shot out older car windows the cost would be lower if they got caught. I hope there's an easy solution or that your problem doesn't suck as much as mine. Good luck.

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Die auto ist immer kaput...