You need to get the schematic for the game, and locate what actually drives the coil. Could be a short in either the CPU or PPB, check the transistors, pre driver transistors, diode and resistors in the circuit.
OK had a quick glance at the schematics, check Q1 on PPB and check Q13 and Q7 on the CPU. These are the transistors that drive the coil. Hope it helps. LAH is a fun game to play.
