found the problem with the latest motor damage (ii had presumed it was the gears stripping causing it to spin, but instead it turns out the gear on the motor has come loose). And ive never had this before. The gears are only pushed on like the some of the older drill motors i first bought, rather than the later ones i got which had the flat.

Was wondering if there was a way I could reattach it on well? as if i try another motor i fear the same thing is probably going to happen with the stress of the motor? there appears to be glue one some of the motors gears probably to help with the push fit, but if that wasn't strong enough, how do you think i should attach it?
could attempt to glue again with the torque limiter and see if that prevents it, or could i somehow weld them together?
what do you think as im unsure, or should i just do a few tests?