Help with Stanley Brace

This brace was in my parent's attic then basement basement for years but never used. Last summer they were cleaning out and unloading a bunch of stufff and I picked it out of the trash pile. Today I found some old auger bits in an old tool box and thought I'd give the brace a trial. I can't get the jaws to tighten up around the bit and I'm thinking something is getting caught up in the ratcheting mechanism. Has anyone ever taken one of these apart and tried to repair it?