Found the little 2 pin switch just at the ball eject site. Gave it a wiggle and red diode comes on and off, so something going on. I think i'll have to get a new one from USA, or keep trying locally. Looks like a mongrel to try and replace.

Before you order another board from the US...

It sounds like it's nothing worse than a dodgy connector, or maybe a bad solder join between the pins and the board.

Give the pins and connector a good dousing off Isopropyl Alcohol (Bunnings) then push/pull the connector onto the pins a few times to "clean" everything up a bit.

Check the white connector itself and with a small flat-blade screwdriver see whether you can close up the connector that grabs onto the pins on the board.

That may well "fix" it for a while (maybe years!). If it does help, then just cut the connector off and solder the wires directly to the pins.

If it doesn't fix it, take the board off the machine and have a good close look it it and see if you can spot any cold solder joins.