Originally Posted by
vintagerando
Something is stopping me from screwing in the cup on the non drive-train side. Of course this was by hand, no tools, with easy pressure.
It looks like there are some burrs, sharp metal fragments coming from where the chainstay tube meets the BB. Maybe that's what is catching. Could the end of the chainstay tube been disturbed the last time a bottom bracket was removed or installed?
If it is Italian threaded, both BB halves screw in clockwise.
If it is English threaded, the drive side screws in clockwise and the non-drive side screws in counter-clockwise.
You probably know this, but screwing in the non-drive is counter intuitive and if you aren't thinking about it, it could be your problem.