The largest problem with tonearm bearing is too tight. Even a tiny tiny bit too tight is huge pressure in very small areas. Just on the verge of loose is way better than failing to understand even a little tight is way way too tight.As for damaging them mounting a cartridge? (if you are using an automotive air gun?? probably.) Otherwise not likely unless you are ham fisted Mr Bungle himself.
tonearm bearings. How do we attach cartridge without ruining bearings?
I have always taken the tonearm or headshell off of table to tighten cartridges. When a cartridge is tightened isn't there a possibility of ruining the bearing in the tonearm if the arm is not removed to allow tightening of cartridge fasteners?