When you run slide out does the slide stop or still at angle?
This is the slide stop nut rested against the stop plate inside the compartment.
This is how the stop rod looks with it attached to outside slide wall metal bracket.
Check the two plates the one where the rod travels through and the one attached to the square D with the holes for cog wheel that the plates have not broken there welds to metal that they are attached to. Your looking out under the slide opened.
What you may have heard was the cog wheel jumping the holes in slide rail and you need to loosen the nuts on shaft to get everything back in line with slide closed.
The slide when brought in should stop when the outside slide wall hits the recessed main wall of coach and it should stop, the control will sense the higher current draw and cut off power to motor.
Here is the old slide spec
which you would have.
Here is the new slide spec
which will have better pictures of the stop rod info and explaination of operation starting at page 26 read that information about the hardware of slide and its operation to understand how your slide works.
If nothing is broken and no adjustments have been made to the control pot the slide should close normally until you can have someone look at it unless you can see what has happened under the slide.
If you released the drive shaft nuts with help you can push in slide with out the motor, I would use motor to get slide up the ramp first than use the help to push in slide. Trans torque bushings
Here is a old thread
on same subject.
Make sure you have all fingers clear when operating the motor it can crush body parts.
Slide info can be found in QT's 1 & 2.