[gkagan]

which is to say:

I have a ca. 2005 CA M4. It was stock and running fine, and I decided to switch to LiPo and put in a MOSFET. When I disassembled it, I noticed that the cylinder head was actually broken, so I replaced it with a brass one from element. I wired in an AWS Pulse FET unit and reassembled the gun w/o problems.

Now, the gearbox runs fine, nice ROF, smooth motor sound, etc., but when I fully reassemble the AEG, it won't fire. I get the gearbox whirring away going popopop, but I get that dead "the barrel is blocked" sound. It *seems* like the nozzle isn't pushing into the hopup unit appropriately to seal with the hopup rubber, and I know this causes huge problems for lots of people. It appears that the spring ont he tappet plate isn't strong enough to push the nozzle into the hopup. When I have the mechbox out of the gun, the nozzle flies back and forth no problem. It only happens when i put it into the hopup unit. If I load the magazine tube with bbs, and fire, they all shoot out violently.

So, PLEASE tell me: have I correctly identified the problem and if so, how the hell do I fix it. The cylinder and piston heads are the only things I've changed, and the nozzle moving when running disassembled would indicate to me that it is not getting stuck on the new cylinder head.

Thank you