Greetings and Welcome
Please don't start beating on your silde with a hammer and chisel
Sounds like the motor and shaft are not aligning properly.
IF they aren't you'll need to move the slide in
or out till the motor drops into place, gently shaking the motor will help.
When/if the motor drops into place
stop! Re install the locking screw. In the screw is damaged or missing take 1 out of another slide then a trip to Lowes etc will get you a new one.
Good luck, keep us updated and please post some pictures.