I have a Crosman 1300 that I have had for the last 40 years since I got it for Christmas when I was 8. Over the years I have abused the heck out of it with little to no maintenance other than occasionally dropping a little Hoppes #9 oil down the tube. Well I got the dreaded air leak on pumping. I ordered a seal kit and installed it over the weekend. Now it will at least pump. If you pump slow no air goes in the valve. When you pump fast some goes in while some spits out the barrel. It will fire if you use it right away. If you let it sit for a minute or 2 all the air leaks out. I replaced all the seals in the kit and used some Hoppes when putting it back together. Any ideas on what is causing the remaining issues.