Not sure if the 2000/2001 mechanisms are the same...
These pictures are from a 2000 Sunline slideout. Please let me know if this is the same mechanism you have.
First picture is one of the rollers, that are under the arms..
The gear, that retracts and extends the arm...
Motor and drive assembly...
The bearings in those rollers can get to where they drag and cause a lot of friction, when they are under load. It's possible that they need to be replaced, to allow the slide to move more freely. If it's only the rear of the slide that is dragging, I would be looking at those bearings and rollers very closely. Maybe have someone hand crank it, while you are watching.
A word of caution... When hand cranking a slide, DO NOT use a lot of force on the crank handle! With the gear reduction these things have, it is very very easy to over-torque the whole drive mechanism! The access for manually cranking the slide should be on the opposite (Door) side of the camper.