I think it's important we're all on the same page here...
Tapered roller bearings - the kind in our trailer wheel hubs - consist of:
1. Tapered roller bearing assembly - cone shaped - called by mechanics, the CONE.
2.. Bearing cup - to accept the CONE assembly - called the CUP.
The CUPs are intended to have a press fit into their part of the assembly - the wheel hub - are aren't meant to move once installed.
The CONEs are intended to slide onto the axle shaft with a close tolerance, and are held in place with the outer wheel bearing pre-load by the nut/washer, etc.
We all know this stuff - let's just get on the same page and call em' CUPs and CONEs...to avoid confusion...
I believe most spinning CUP problems occur due to wear causing the CONEs becoming loose to the point of overheating and distorting the CUPs enough to loosen up, also lack of lube and improper adjustment are probably the chief culprits...
As some have mentioned before...once the CUP becomes loose, it's time to replace the wheel HUB/DRUM! It's just not cost effective to try and fix em' - they're too cheap!
Ray & Pat; Morada, CA