We should have the same slide drive system in our '07 which runs perfectly.
Since you say the slide moves well manually, the issue must be a binding in the drive set. Something must be out of adjustment or damaged.
If it were me, instead or re-engineering the drive, I would go part by part from the main slides. Check for damage and adjustment.
These slide drives are amazingly strong and carefree if everthing is set right...like:
A while back, a metal handle broom shifted inside the bin containing the front slide channel and caught up inside the slide channel. When retracting the slide, it stopped when the channel contacted the broom. I checked the slide exterior and retried to retract 3 times. On the 3rd attempt, the broom handle was flattened and cut in two, pieces falling into the bin floor
Thankfully, the slide channel was not damaged. And now I know to ensure there is NOTHING up in the slide channels.
Blocked slide channels are obviously not your issue, or you could not move it manually...the problem is surely in the drive set = motor or the rack and pinion.