PSG-1 Full-auto, kinda, sorta, sometimes.
 

If anyone can help I will owe them a coke/beer/first born if I meet them in person.

Correct me if Im wrong but I think this is a gear timing issue. The gun is unpredictable, it will fire fine for a bit an then go an a tangent of FA, burst fire, no fire, and then be fine again.

Please help,

Rob

I know this is an old thread but I know the answer to this question.

Back when mine was having this problem I found that the spring release lever was being eaten by the sector gear nub. The spring release lever also controls when the switch disengages from the trigger. If you have this problem you need a new spring release lever.