"The fuse element is made of zinc, copper, silver, aluminium, or alloys to provide stable and predictable characteristics. The fuse ideally would carry its rated current indefinitely, and melt quickly on a small excess. The element must not be damaged by minor harmless surges of current, and must not oxidise or change its behaviour after possibly years of service."Spelling correction just for you Geoff
Re-read that last sentence:
A fuse can age with inrush currents ect, I believe the fuse mongers are prying on that.
Just change your old fuse for the same 10c new one, instead of paying >$100 for a voodoo fuse, that can be a danger if overrated .
Cheers George