Two things come to mind. One the drive head (gear box) has failed. Remove the cover from the gear box and see what is going on in there. Second, do you know the button you push to lock the drive so can remove or install (tighten) a new wheel? Make sure it is releasing. Most of these are spring loaded and if that spring fails the lock mechanism can stay engaged. Hope this helps.
Answers & Comments
Two things come to mind. One the drive head (gear box) has failed. Remove the cover from the gear box and see what is going on in there. Second, do you know the button you push to lock the drive so can remove or install (tighten) a new wheel? Make sure it is releasing. Most of these are spring loaded and if that spring fails the lock mechanism can stay engaged. Hope this helps.