[Tom Wesenberg]

You need the correct wrist pin to match the center lock connecting rod upper bushing. The O ring is in the center and is expanded by pushing a tapered slug through in front of the wrist pin. Someone tried a mix and match and messed up and that's why the wrist pin slipped to the side. At least that's how it appears. If you buy new pistons with wrist pins, they should come with the end locks, so you won't have to mess with the center lock O ring.