Ok. More work done on tests and the shorting definitely was the wires to the WUR. Fixed that and now the fuse no longer blows. I have assumed the Supplementary Air Valve and Auxiliary WUR are the same thing. Looks like this
I’ll take it for a long local run next and see if the shorting was causing the original issue. If not then I’ll start the swaps as suggested. Yes I do have the old coil still.