[Dark Skies]

Hmm. How far downline from the fuse have you been able to check? Have you checked the individual prongs that the fuse sit in? These often seem to overheat and lose their spring. Often times the fuse becomes corroded - even though it looks fine on a cursorary inspection. How far down the feed can you get current flow when earthed? Sounds daft but have you cleaned the fuse conns. and run a meter over them? Break in the line further down?