I have an FX Stage 4 turbo pump but I think it may have an issue with a seal as it's not pumping air properly. If you cover the valve and pull up there is resistance and when pushing down there is a little but when you hit the end of the cycle only the slightest bit of air blows out (literally a small burst) - any thoughts as to what it may be? Is it worth getting repaired or will it cost too much?

cheers