I have a GT18 (917.255919) which has a problem... Initially when I put it into reverse the tractor appeared to be bucking. I added oil to the transaxle then shortly after that, it dod not go in reverse. I does go forward. The question is, what can be the problem and how difficult is this to fix? Or should I just try to get another transaxle?

Hi,
The first thing to check is a bent shift lever that does not allow the shift fork to engage the gears. The breakdown of the transaxle is attached and I believe that the item #11 is the fork in question. It too could be bent and not moving far enough. Also, the idlers on the belt could be not tensioning the belt properly; sometimes that will do it by gripping in one direction only.
Peace,
Clarke