If you don't care about the locking feature, I had a cap go bad, kept 'ratcheting' . finally got it off. but it was in bad shape .
what I did, was to drill into one of the holes in the threaded part near the top of the threads, got a long stainless cotter pin, cut the head off of the cotter pin and then used a hammer to tap the cotter pin into the inner part of the cap .
Locked everything together, no problems for about three years now .