Quoted from BigAl56:
Did you replace the dummy light under the playfield with an LED? If you did that the solenoid expander may not be working properly causing that coil to fail.
Well, thank you for pointing me in the right direction! As soon as I put an incandescent bulb back in that spot everything works properly. So it wasn't that the coil failed, it was that that bulb somehow regulates electrical flow, and without it things won't be running at the proper voltage.
As xTheBlackKnightx said on another thread...
"IMPORTANT TECHNICAL NOTE:
DO NOT USE a LED in the SEB lamp, as this will not work in the circuit theory based on necessary voltage unless the circuit has been adjusted with resistance based on a standard Ohm's Law calculation. A lot of new owners do not seem to understand the SEB design technology and why/how it was used. Read the base schematics closely. The SEB lamp is part of lamp matrix, not the SDB, and does not draw power from this part of the game. The proper 6.5v from the SEB lamp is extremely important in order to draw enough current to the MOC3011 opto-isolator on the SEB and activate. I have already seen young technicians not understand these aspects and make this mistake repeatedly on this series of games.
The SEB lamp is not "just another feature lamp".