Ok final message for the night.
I unplugged the counting meter from the front and connected it up to 9volts - sure 'nuff the counting meter added one to the display.
I'm unsure if it's this thats causing the problem (but they are definatly not changing number when coins are inserted / paid out)
I think a circut tester on the wires will let me know or not.
Any other suggestions welcome. This is the first machine I've worked on since I was a kid and had Barcrest Autoroute.
Cheers
bOing