Please post an update when you have the parts and have completed the repair. This is high on my list of little annoying things to fix.10 year thread revival, looks like i have the same issue for years. the electric motor moves my seat as it should, but the seat rocks slightly back and forth when driving and braking. I had new leather put on, and bolts tightened, but it still did not make a difference. I been looking at other problems that has come up with these electric seats, and it looks like the track gear gets worn out and needs replacing. I wonder if that is also the solution to our problem.
http://www.supraforums.com/forum/showthread.php?645423-Driver-seat-repair#post11877850 shows the discussion and place to get the parts. I am ordering and going in head first on this myself.