Awesome, Ian, Thanks. Will do. I love this game, it is very nicely balanced, there are a bunch of different things to go for that are all lucrative. Unlike many DMDs the optimal strategy regularly changes as the ball progresses. I have had this game in my collection 2 years and it is still heavily played by me and others. 

Here is another suggestion which came from Pinside
"With the number of balls flying around and the number of switches being hit simultaneously I would suspect a shorted diode somewhere causing a phantom switch closure on the outhole.
I don't have schematics handy to suggest which diodes to check, you may just have to systematically test them all."

Cheers, Greg