I recall seeing a fellow with a mom and pop air gun shop selling plastic jigs to fill in the holes in the main tube during valve instillation to prevent clipping o rings. I have tried getting in there and lightly sanding the edges but keep clipping the seals. Sometimes it leaks down immediately and sometimes I can go as long as four months before it leaks down. This has gotten to be such a pain I have rediscovered the joy of my Diana 34 springer while the Mrod sits gathering dust because Im tired of fooling with it. I had saved a link to the site but my hard drive crashed and now I cant find them on an internet search.