I own an old Raleigh steel frame ('89) and wanted to install a cartridge bottom bracket (Shimano UN55).
I noticed it was difficult to fit it in the housing. When installed, the square taper shaft showed considerably more friction when turned.
Also, when I took the BB out again I saw rubbing marks on one side of the inner face of the lock ring, but only on one side. The threading itself is not damaged. When installing only one side of the BB, everything goes in smoothly.
To me it looks as if the BB housing is somehow misaligned. How do I measure it? And how do I treat it?