That's the unit that was giving me hassles "J"

I don't have the schematics, but I'd like to try something. With the machine off, remove the clip from the "J" relay and let it "hang" - but be careful that it is not touching anything as it "hangs". Switch the machine on and start a game. Use the same method you used before - thump your fist on the playfield to cause the phantom scoring.

Still happening ?

Try cleaning and reseating the connectors below the relays.

Still happening ?

Can you tell me (from the schematics) - What the three relays are called ?