[Datawraith]

Hi.
I could really really really use some help.
Okay, so I have a JG G36C.
Stock, it fired 380 fps, too hot for indoors, so I had to do some tech work to detune it to 350 fps.
I bought an M90 spring and replaced the spring in the gearbox, and put it all together. (This actually took quite some work in changing the shape of the top of the spring because JG, being a China clone, had a retarded design and bent the spring into a hook to mount properly.)
Upon reassembling it, I noticed my hopup chamber was cracked, and I decided to see if I could repair it. So I ABS-cemented the chamber back together, when I realized I had lost the nub. After doing some research, I cut the end off a BIC pen and stuck that in as a temporary fix.
When I test-fired my rifle, the BB went about 10 feet, then dropped; I can't even begin to describe how wimpy it was.
That described how the rifle fired when it was adjusted to no hopup. As I dialed in the hopup, the rifle became more accurate and shot further and harder. However, this only worked for semi. No matter what I did with the hopup adjustment, full auto just dropped BBs out my barrel like there was no hop. I have to add that even on semi, it would still occasionally (every 10th BB or so), the BB would just drop out like there was no hop.
Can somebody give a possible reason for this? Is it because my hopup chamber was cracked and is maybe leaking or something? Or is it because my BIC nub sucks and I have to get a new legit one? Or maybe the M90 spring is just suck-ass wimpy? Or do I just suck at teching and seriously fcked something up?
Oh, and one more thing that's kind of unrelated; I contacted about 10 AV'ers about 2-4 months ago in both K-W and Markham (I'm a uni student), but not a single one replied. Could somebody please help with this too?
Many many thanks!
Datawraith