The diode on the coil is probably fried again.
Sometimes I've tested the diode, and it tests good, so then I only replace the driver and pre-driver transistors, all is well, start a game and a minute later, the coil is locked on again.
So now, the flaky diode has killed the driver transistor again.
The moment the game is powered up, the coil locks on, even before the MPU boots.
I'll check the driver chip 7402 and make sure it's not cooked.
The fix usually is to, all at once, replace the Diode on the coil 4004, the Pre-driver and Driver transistor.
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A bad (or missing) diode will kill your transistor instantly.
Sometimes a flaky diode will test good, but the first vibration from the coil being triggered will make it momentarily go open, killing the transistor.
Make sure the new diode's band faces the red wires.