G&G R4 Nozzle/Feed Issue

[Darklen]

Searched around and couldn't find a specific problem/fix so here's the scoop. I'm replacing a broken tappet plate in a clients G&G R4. Not a biggie, it's a known issue with G&G and I've done 3 already, some guns with extras installed, one without, all with zero issues. This one is puzzling me though.

I replaced the spring guide and cylinder/piston head (with systema silent set), but didn't have a better tappet plate around other than a used TM one. So I put that in to hold the client over until I got a better one. Put the gun back together and now the nozzle (the stock one w/o oring) is sticking out about 1mm to far forward and bb's won't feed. I took the entire unit apart, checked to make sure I did indeed assemble properly (I had), reassembled, same deal. Cycling mechbox does nothing, nozzle resets to about 1mm too far forward. wtf??? For shits & giggles I put the upper/lower front receiver pin and wiggle the halves so the nozzle will allow bb's though, duct tape halves & test fire. Works fine, but through chrono fps dropped from mid 300fps to mid/high 200fps, bad seal, not acceptable. I pushed on the nozzle and it will move back about another mm. Cool, maybe the TM one is worn a bit too much. Aquire a new Guarder tappet & install. Exact same clearence issue. Start pulling hair out (if I had any). I dig through my old modeling parts and find some brass tubing that will fit over the pin on the sector gear that operates the tappet. Cut and superglue in temporarily to test. Same damn thing, but the tappet is fully retracted now with no more rearward movement and it's still to far forward.

I can not find anything the plate could be rubbing or hitting to stop it from moving. The gun worked perfectly until the tappet plate broke. I can't figure this one out. Everthing pins together properly, the hopup chamber is sitting right, everything is nice & tight together.

Anyone have any ideas before I shave my head & become a monk?