Thanks Mark for the offer

All led's are on except 104

Are you checking the leds on the CPU also?  Or just the leds on the power/driver board?  Led 104 is on the power driver board.  The CPU is the board to the left of this...

See below from Pin Repair Guide....

WPC-S and prior uses a "Dx" designation for its CPU LEDs. WPC-95 uses a "LED20x" designation.

D19/LED201 (blanking): at power-on should be ON for about 3 seconds (1 second on WPC-95), and then turn off and stay off. When D19/LED201 is on, the blanking circuit is disabled (and will not allow any coils to be energized).
D20/LED203 (diagnostic): After D19/LED201 turns off, D20/LED203 should stay flashing permanently while the game is turned on. This indicates the CPU is "running".
D21/LED202 (+5vdc): this LED should ALWAYS be on. It indicates the CPU has +5 volts DC power.
Problem Power-On CPU D20/LED203 (diagnostic) Flash Codes. If D20 does not flash continually, here are the flash codes diagnostics:
blinks ONE time: U6/G11 CPU game ROM bad
blinks TWO times: U8 CMOS RAM chip bad
blinks THREE times: U9 WPC custom chip bad (pre WPC-S), or G10 Security PIC chip bad (WPC-S and later)