take it to a paintball repair shop or send it to macdev. hopefully you havent stipped the threads on the body. if not, a pro should be able to help you out. if you force the drivetrain out, or try taking the bent screw out through the hole you run a risk of damaging the threading on the body and seriously ruining the gun. i wouldn't mess with this unless you know exactly what your doing.
dwell is the ammount of time in miliseconds the solenoid is sending air in to cycle your bolt. having too low of a dwell doesn't let enough air in, and the bolt wont cycle, or will give inconsistent velocities. too high of a dwell can cause your marker to be an air hog.