These LP injectors are notorious for sticking. I have three FG35 Komatsu's that do it constantly. At the end of the injectors are tiny o-ring seals that bind in the chamber. Dont know if this is your problem, flushing out the fuel reg per manufacturer recommendations helped. Gotta do it with the engine hot though. Also make sure your coil resistances are within range. Ed T is right about the training, if you do not vent the fuel system prior to removing the injectors, they will pop up right in your face when you remove the last screw, even in front of the lock-off.