Tracer Rear Shock Question

Has anyone had a reoccuring problem with the rear shock getting nicks/scrapes in the shaft? I've had the thing rebuilt twice this year. Basically the shaft gets worn on the underside where it wears through the coating the thing starts losing air pressure. Maybe it's just bad luck but could the frame b out of alignment or something that is causing this? I checked the rear linkage for tightness, everything was rock solid. So just throwing this out to see if anyone else has had something similiar.