In reference to one of these BB's:
My kid had successfully chamferred the left BB cup's splines, until there is no useable spline surfaces left. metal alloy, not plastic. What happened was the Right cup worked it's way loose (by design!) and he just kept riding it until the left crank abraded the left cup to nothingness, that, and he couldn't pedal it any more ;).
Q1. What is the recommended extraction method for the mucked up left cup? Dremel and cold chisel? Q2. Does the LBS sell just the left cup? Q3. To prevent a repeat, is it advisable to put some Lock Tite on the Right cup? From what I can tell, the BB was never faced properly, and the RHS cup will continue to work loose, given it is a LH thread and is on the RHS.