I've got a couple flashers out. Number 3 on the back panel is out but the paired number 3 on the playfield works, as does the #3 solenoid, so I believe I can rule out the driver board and assume this one to be a bulb/socket issue. Number 4 is out in both locations. Solenoid 4 is a spare so I can't test the electromagnetic device. Can I perform a typical "ground the transistor" test as I would to test a solenoid, stopping the test on Flasher 4 then briefly grounding the tab?