I've got a mg34 semi auto that has a serial number Looks like a tnw from bottom but does not have the serial. The front 2 inches was missing so I found one from a cut 34 and had lewman arms assemble it. Problem is that the back portion 1 lacks an ejection port cover hole 2 the barrel in her hole is drilled for the big part of the plunger but not the smaller part that slides into the spring. I can't use it as is Who can i send it to to do the machine work