Hey - after a year of having the valver, and on the third or fourth attempt, the window is no longer held up by some wood!!!

However, the second hand motor I have doesn't work 100%.
The window goes 80% of the way up with no problem. It then slows down to a crawl. It still goes right up, just slower.
Each time I do it, it increases the speed a little, but its still slower than normal.
Any ideas?
Is the mech on its way out? Have I positioned the window wrongly??
I'm keeping the piece of wood in the car at all times just in case it decides to drop.
Cheers.