I've heard that this was a pretty common problem, but I don't feel like sifting through 100's of threads just to find a solution.
Okay, so I recently got a broken SLG. When I first got it, the noid would stick and wouldn't even dry fire. I fixed that by messing with the sear, but now it shoots full auto as soon as I air the gun up. Something like this, except I don't even pull the trigger:
I still think the sear spring is the key.
You said you tried a pen spring, but there's no gauruntee that it's strong enough to hold the sear up, or even stronger than the stock spring.
Try going back to the stock spring, but stretch it slightly first. There's a very fine range of proper spring strength where it will be strong enough to hold back the bolt at rest but not so strong that the solenoid can't cause it to drop the bolt.
Does it still fire randomly when the gun is turned off?
I really laughed a lot when the gun went mad @ 40 s ; I know what you were feeling because i have just finished working on a friend's slg : same symptoms .
What I did :
- with a squeegie, I dried all the grease around the engine, and on the sear
- put teflon around the backcap ( so it won't come off )
- set the fps to 280 ( gun will runaway with lower pressure , and won't also work well if too high )
this is an issue with the pressure... adjust your LPR while you are aired up... keep messing with it until it stops. then re-adjust your pressure to desired FPS through the HPR. viola! should fix this problem... if not, then your sear is jacked up
Reason why i know this: ive owned an SLG for 2 years now, mine did this when i first got it. fixed it, and it shot like a dream... went to a tourney and somebody sabotaged my bolt... took a razor to it... got a replacement and found out my main body is cracked, so im looking for a replacement... lol