So if you get a ball into one of the eyes, the outhole kicker fires repeatably so if you loose a ball, it just pops back out again, ready to shoot... this continues until you get a ball in the other eye and mutiball starts then the outhole kicker stops. It doesn't matter when eye the ball is in, it happens every time. I've never played the game before picking this one up but I am sure that can't be right, you can keep scoring as long as you want to by avoiding the other eye!

Anyone have any ideas?

Yup, that was it. It just needed adjusting, it was being held on.