Find the motor and gearbox assembly. You will see there is a shaft that comes out of each end and drives gears. Determine if the gears are OK but that there are connecting bolts through the shafts that may have broken. Replace any broken bolts and retry operation. If you find that the gears are jumping up over the teeth on the rams, then you may have to get some help to cut flat washers to fit as shims to force the ram up tighter into the teeth of the gears. There is also a brake on the motor that if it has electrically failed must be manually taken off, but usually the motor will do nothing when is goes bad. You might get some extra help and have people push on the outside wall of the slideout while using the motor to bring it in and see if you can get it past the binding point. Good luck and keep us posted.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7