Issues with master locks are hardly new- back in the 1980s, I downloaded a file from a BBS explaining how to open a combo lock (basically by pulling on the shackle while turning, and a few other tricks.
It's still online: https://cdn.preterhuman.net/texts/anarchy_and_privacy_contro...
Oh my god, I remember doing this technique on my lock, I remember doing this in the early BBS days, I remember learning this from a short text file. I'm 80% sure it was this file!
Thanks for unlocking this memory for me!