Originally Posted by
robertorolfo
For the record, the BB is Italian, and the factory thread lock is long since worn away.
Then you should replace the thread lock with new Loctite, at least on the DS cup. That's your problem.
Put the Loctite on the DS cup, insert it to the proper spot and let it cure. Then assemble and torque from the NDS.
If you don't want to do that, give the DS cup a healthy wrap of teflon plumbers tape to keep it from spinning.