Ok - heres an update.
It has a dodgy switch but I cant see how that would cause the problems this game appears to be having.
First I will cover the main issue.
(1)
The issue that it starts in modes and jumps all over the placeYou start a game and it goes straight into one of the modes ( the gameplay modes in the chain like Blackout, Pursuit or Bad Impersonator etc ) my neighbour tells me that normally you have to drop the JUDGE targets and then get the ball into the sniper tower to start a mode - then play the mode, then the game goes back to normal and you repeat process for the next mode that you need ( he has owned this game for 5 years ).
One thing I witnessed whilst in the middle of Bad Impersonator mode , the game just 'switched itself' into Pursuit mode.
Also - There is a JD bike that must roll across the DMD at certain times in this game and it gives you 500,000 each time - this bike never stops !! It will soon need new tyres
Multiball just starts by itself at anytime as well.
(2)
The dodgy switchSwitch 64 , the Left Ramp Exit opto is fine when you have the playfield up ( right up ) against the backbox, however, as soon as you lower the playfield to normal position and go into Switch edge test it is jumping non stop between open / closed.
If I went into Single Switch Test and moved my finger between the opto switch it appeared fine then too.
I really dont see that causing the main problems going on with this JD but thought I would mention it.
The machine reports NO errors at start up tonight BUT my neighbour said yesterday it did AND it pointed to that switch.
I hope this makes some sense to someone.
Cheers