I have not had this problem with my SVX but on my Loyale wagon.Drivers side would not work every once in a while.I checked out the track and it was fine. I ended up taking the end cap of the drive motor off and cleaning the brushes and the armature with electrical cleaner. Put it back together and have not had a problem since. The brushes were pretty worn. I am going to look for another set at the salvage yard just in case it starts acting up again. The drive set up is most likely the same type on our SVX's. Hope this info might help fix your problem.
