Yesterday I was replacing my pop bumpers and had an issue with the threads on the metal posts not wanting to come off the metal yoke. I think over time they just got smashed together and I ended up braking the yokes trying to get them separated. On one set I actually cut the upper part of the metal rings with metal shears so I could unthread them. This worked but felt like overkill. I just ordered new yokes so it wasn't a big deal but I was thinking this must be a common problem and someone must have a trick for separating them non-destructively.
If it matters it was on a Stern LotR.