All good stuff thanks everyone
As it happens I've got a suitable Spring balance for checking the pull off Strength of the magnets
Some of the things listed have been checked some haven't. Distance is proving a problem so if not sorted in the morning I will derig and bring back to home airfield in any case so I can work on it properly
Didn't occur to me - or my engineer - that fuel pump Spring going week could cause increase pressure spikes
Anyway - it will be a lot easier to sort once at home