Make sure you have all your on/off orings installed. The on/off consists of 17 through 23. If you have a ULT in place of the on/off, pull all the shims out but say 2.
Your on/off is more likely your issue. Wear on the sear (not shown), the bolt (16 and 2), main spring (1 and 15) or a very small leak at the valve pin assy (30) can cause it too.
If you don't have a parts kit. I would highly suggest getting one. If you have a lvl 7 bolt, go for a RT kit, if you have a lvl 10 installed, get a Xvalve kit.
http://i283.photobucket.com/albums/k...xplodedff7.gif