In addition to above suggestions, let the game cycle through all the solenoids in test. Make sure all are firing in order (solenoid chart in manual) and make sure only a single coil fires each time.
Also, in switch edges test, wiggle both trough opto board connectors and make sure the shooter lane switch is working properly. Lastly, also in switch test, pound on the playfield with your fist, to make sure there aren't any borderline switches. May not be a switch issue, but trough opto board connectors and shooter lane switches need to be checked closely whenever extra balls are being kicked out when they shouldn't be.