• Did you put plenty of grease on the threads of the shell first? Without any such stuff a thread that size will heat up and bind due to friction, esp. if the shell is aluminium. You only need to face if the BB is not a sealed cartridge type, but you may need to chase the threads if they are rusty, very dirty, or after too many aborted attempts (without grease) fncked! Basically you should be able to screw at least one cup+cartridge (if it's sealed type) most of the way in by hand - if not summat's wrong.

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