The plan if I can not find another in my "pile of stuff" is to solder onto the terminals and run an ATE type in line fuse holder. Last time I needed one I found one in side a fuse holder from a car I must have stripped 30 years ago. Fiat plus has one of these in line fuse holders for sale NOS with the fuse for $10 which would be the easy way to fix this. I parted out Fiat's for a living in the early 1980's then some time in the early 2000's I came across a guy moving who was selling his Fiat and Abarth parts. He was not sure what he had, nor was I. We came up with a really low figure I thought for everything, he would not know for sure what he was selling nor I what I was buying until we loaded the parts. Was kind of fun, I ended up with some NOS abarth parts as he had just restored and then sold a 750 double bubble, some 600 parts, parts from an 850 race car, some multipla as well as twin cam parts. I still do not know what all I have. The parts were stacked as high as the cab of my flat bed F350 and filled the entire back seat. Life is tough, I am having to not drive the Lancia until I get around to doing this instead I am driving the Mondial.
BTW, the fuse did not blow, it simply broke from age.
Jay