Beaky,
Went out and check the voltages, they are as follows (pins go from right to left on the machine)
Player 3
Pins 1 - 16
-0.8 3.7 4.2 3.8 9.1 82 -93 3.2 2.9 3.2 0 6.4 2.3 3.8 0 5.4
Pins 24 - 39
3.2 0 6.4 3.8 6.4 0 5.4 -95 3.2 1.1 83 0 6.5 0 6.5 -1.3
Player 4
Pins 1-16
-1.4 6.7 0.5 6.8 16.7 17.4 -10.8 5.4 0 5.4 3.5 6.5 0 6.4 1.9 5.5
Pins 24-39
5.5 1.9 6.4 2.5 6.5 1.6 -3.7 -12.5 -3.6 -0.8 18.3 -1.5 3.7 -1.9 3.7 -2.1
The other thing i noticed is that some seemed to fluctuate a bit, dunno if this was when the display was meant to be lit up during attract mode?