Latest update is it looks like I am getting the right power at the monitor connector once I measure it the correct way
I measured at both the power board end and at the monitor chassis end of the power cable and got the following:
Red to Brown wires (lugs 3 and 4 on transformer 0-128) reads 136v
Orange to Yellow wires (should be 240v) reads 247v
Next steps are to send Grant on UKVAC some pics of the monitor chassis to see if something got damaged in transit or if I've connected something up wrong their
So it looks like I didn't really need to remove the power board but it has meant it got a good clean and I now know a bit more about my arcade game 

I measured at both the power board end and at the monitor chassis end of the power cable and got the following:
Red to Brown wires (lugs 3 and 4 on transformer 0-128) reads 136v
Orange to Yellow wires (should be 240v) reads 247v
Next steps are to send Grant on UKVAC some pics of the monitor chassis to see if something got damaged in transit or if I've connected something up wrong their

