Hello. I have tried Gumtree and some wreckers. Amazon is American isn't it? Are the window motors repairable? Is there a contact or part inside that can be cleaned or adjusted or replaced?
You could take the motor from the window behind. I think it's the same but haven't checked. Then you have all the time & sanity in the world to find another.
Alternatively, you will find out it's not the motor that is the problem. Try see is there are any relays involved, how these are earthed, etc.
Bookmarks