[sluggo]

Sounds like the set screws in the collar came loose and there is actually a pair in each threaded hole one on top of the other so remove the outer one loosen the inner one and push on the collar about as hard as you can with one hand then tighten the screw remember there are four set screws per collar two in each hole. They are very reliable but occasionally need a little maintenance. Probably made by pss seal you can watch a video online about how to do the work.

thanks so much,but I swear, there is no locking nut, just 1 screw in each, probably need to fix that!