weird cycling problem...

Ok folks, I was all proud of myself earlier today for putting a new metal hopup in shorty M4. Of course, this requires taking the gun right apart and then back together again. The first time I did it, it went back together great and cycled just fine. However, I later realized that I'd left out a barrel spacer, so I took it apart again.

It went back together seemingly ok. But when I plugged in the battery it fired a couple times, even though it was on safe. I flicked it to semi and it started shooting on auto...I wasn't holding the trigger.

So, I took the battery off and noticed a spot on the deans connector shielding where metal was showing through. I taped over it with electricians tape, put it back together, and it's "almost" better. Shoots on semi, but on auto it sort of...hard to explain but it doesn't stop immediately after I release the trigger.

Is this a further wiring problem? Something inside? Fire selector problem? I'm out of my league here.

This is my M4 CQB shorty. I can't really say it's a TM since nothing left on it is still TM, but it's a standard M4 mechbox in a G&P metal body.

[MadMax]

My guess is that your switch block is jamming in the block housing. If the trigger return spring pulls the trigger back forward reliably, the only other thing that could be holding your motor current "on" is the switch block inside the mechbox. There are no other components that can close the circuit path that are timed to a trigger pull. It seems that the hop up work might be a red herring.