Not too sure whats happening here, do you hear any clicking when you pull the trigger the first few times?
If not, DE-GAS THE GUN, take the bolt, velocity adjuster, spring and striker out of the back of the gun (pull the field strip pin out).
Now, switch it on, and look through the back of the marker and pull the trigger. Does the sear pop down really quick? If it doesn't your battery is either dead or not powerful enough...try duracell or energizer........either that or your solenoid or board are messed up.
If you have changed any of the dip-switch settings, set them back to how they were when you got it. (or semi-auto mode)
If you do get the clicking, then it may be a gas problem....dunno what could be causing it to only fire after a few pulls.
If you aren't too happy fiddling with things yourself, ask Kingman about it or take it to an airsmith, or your local site.