Piston Problem

I was out at a game today and I noticed my CTW made a weird noise and then stopped firing. The gun still "fires" but the air nozzle does not move. I removed the cylinder and checked for wear and there were no issues. I disassembled the cylinder and there looks to be no issues either, everything is intact. Im not exactly sure how the air nozzle works with the piston head but it looks like it clicks in and is pulled back when the piston cycles? That whole setup seems to be fine also. When firing it sounds like a muffled thump. The piston isnt cracked, no wear or shavings anywhere. I am really quite baffled by this. Any ideas what could be wrong?

Well have you ever heard of Occam's razor? Well apparently I'm an idiot. Finally sat down to really look at the issue and the barrel was jammed... Still works like a champ after I cleared it. Can't believe I never checked that... Oh well at least I got to have some fun using my KMP9 for once.

Acctually, after reading your issue, that was my idea to suggest to you - check the barrel!