Ist pic shows the board repaired for the 2nd time.. all good now, it has been left running for several hours now with no problems.
As I mentioned earlier I had to repair the display regulator circuit again, the BUX85 I had fitted failed. This happed while I was testing other game functions as well.. so once again I replaced ALL of the transistors and diodes, this time using a BUX84, which saw the HV regulator functioning normally again. To make matters worse, when the reg failed and sent 230 volts thru the NEW display glasses I think it damaged one of the new glasses.. some segments in one display intermittently flickering now. Well at least the Hv reg is running reliably now.

2nd pic shows a couple of the shorted coils I removed.. a sling coil and a drop target coil. I also need to replace the knocker coil. The Sling coil (a J26 1500) has been replaced, my recently deceased Vortex pin came to the rescue here as it had some Stern coils in it. I had one bumper not working which ended up being the drive transistor emitter lead not soldered properly.

The lamp driver board seemed to be working initially until I discovered some strange goings on in attract mode..
the ‘4 players’ lamp flashed in attract mode which I thought was odd, I started a game and racked up 4 players and watched the player lamps.. all ok until#4 when it didn’t come on.. hmmm.. time to check some connectors! Looking at the schematic, it showed plyr #4 going to J2 pin7, whereas MY J2 didn’t have a wire!! I found it pushed into another position on the connector, one problem solved.

Next problem was the tilt light coming on at the end of a game. To cut a long story short, this ended up being a strange hack I found on the back of the board (4th pic). Someone had put this jumper on the back which effectively linked the ‘tilt’ lamp output with the ‘game over’ (I think, not 100% sure now). Just why this was done is beyond me.  

3rd pic shows the board being tested on my test rig. No other repairs were needed to this board.