Owner had a pack of 10 of these fuses , probably 20 years old. 1 used and
soon failed and 2 of the remaining seven were broken cold-wire fashion, ie
straight. Looks like they were made with no give and fail just from old age.
Where the first filament went to, is still a mystery, my guess is some sort
of weird metallurgy, converting to a vapour. No problem at all with the
"failed" kit , taking less than 50mA in use