Here are the pics of the finished job.  Looks much tidier and will certainly be more reliable and easier to work on in the future.

Tested out and GI all seems to work and no more blowing fuses.


ADDITIONAL INFO
I re-pinned connectors J120 and J121 as per the White Water manual but I’m starting to think that the manual might be wrong (Heaven Forbid!) as they seem to be reversed compared to other WPC games which have the thinner gauge wires at J120 and the thicker wires at J121.

Could any WH20 owner confirm this for me? 

Not too sure if it will affect things as these pins are all paired up anyway between connectors.  Maybe backbox and playfield GI will be reversed?

Might have to come back for another visit Craig.