I have an old Crossman Medalist '22 pistol that has been sitting for about 25 years +/-. Rust on the outside, hard to tell about the barrel. It pumps up and holds a couple of pumps of air, but if you pump it further, it does not increase pressure. I used to shoot this a lot, but....... From what I have seen, a repair kit will cost me $35-50..... Any thoughts/ideas. Thanks.