This problem can be caused by one of a few factors:
1) Your coach is not level (front to back & side to side).
2) The slide is not properly balanced or aligned.
3) The slide stops aren't set properly, causing the slide to "over shoot" the gear that drives the mechanism.
While there can be other problems, my guess is that one of the above is the cause.
Aside from lubricating the gears and gear tracks (assuming your slide is gear driven, not hydraulic) there is little maintenance to be performed on the mechanism. If you choose to lubricate the mechanism, make sure you are using a lubricant approved for the purpose. Regular oil/gear lube/grease is not the answer since it attracts dirt and grime. There are lubricant sprays approved for this purpose.