Ok normally I can get a BB in by hand to the end it turns twice then jams… I have cleaned both BB and the BB housing, LBS job? all threads look fine

Try another BB to see what happens. Sometimes it removes that infinitesmally small bit of grit that’s causing the problem – assuming you are not cross threading it 🙂

What epi said but having a bb cleaned and faced up by LBS might be a good thing.

I find BB threads suprisingly delicate and easy to cross, so I always make the point of threading them in by hand. They need to go in really straight and on mine, if they don’t, they stop after a couple of turns; I guess the threads begin to cross. I don’t know what sort of BB you’re fitting but I still use Octalink cartridge units and find that popping a finger into the axle on the far side when threading them in helps to keep things straight. Cleaning up the threads sounds a good idea too (both the BB itself and the shell).

I was fitting a RF x-type, never had a problem prob nstalled over 30 of them but this is stuck, but off to the LBS today to make sure I dont damage the frame, I only tried by hand 2 turns, just hoping it is not the frame I just brought…………………..