mate of mine had same problem. Having striped the marker he found half a paintball at the end of the rammer. My advice strip it to it's componets and clean. Lube and rebuild. Should work fine. also cheek the low presure hose for breaks or cracks.
pointing back to my last post, what should i be using on the rest of the gun?
regs need vaseline, bolt and rammer need gun oil, what do i use on the seals on the rest of the gun?