For a start, I would try to examine the solenoid area while the ball is ejected. Look to see if the return spring on the lever arm is broken or weak. Check the spring on the solenoid shaft too. Check page 34 of the manual for maintenance information. Also try the solenoid test on pages 28 & 29. Looks like 02A is for the ball shooter lane feeder.
You should be able to examine this with just the door open.