Quoted from Randy_G:this is gonna sound crazy...I'm having the same issue with a F.Spa I just picked up...no white/yellow wire @ A2J3-13
do you remember ever finding that out?
A2J3-13 was used to carry solenoid power to the head for the knocker in earlier games.
Since Future Spa has the knocker in the cabinet, it gets solenoid power from A2J2-2 instead meaning A2J3-13 is no longer needed so it's left unpopulated.