So I have run into a problem I just can't figure out. I know there are a lot of smart minds that browse this forum and I am hoping they might be able to help.

I have a x valve with level 10 bolt (zero shims & 1.5 carrier), stock on/off assembly with 0.750 pin, and gold spring. When I pull the trigger it has sustained auto response and then stops when I release. This valve came from a tac1. I spent my saturday trying to narrow down the problem by switching parts with another identical tac1 set up that shoots without problems. I started by verified all o rings in the level 10 bolt and on/off assembly were ok and lubed. The velocity was adjusted during the full auto bursts with trigger pulled and didn't seem to change its behavior. I then changed the on/off pin with a new 0.750 without success in eliminating full auto. I started swapping parts with the tac1 that runs flawlessly. Swaped trigger frame with rail and sear, didn't fix. Then I moved onto swapping on/off assemblies and didn't fix the problem. I then put the good valve with the bad valve rail, body and frame and found it shoots with no problems. This is how I started zeroing in on the valve. I was a little shocked that the good valve's on/off assembled in the full auto valve didn't fix the problem. This is where I am not sure where I go from here. It's not the sear or on/off assembly which are what I thought are the two most common culprits to the problem.

Any help would be greatly appreciated!