Fried ECM
Will a fifty year old fusable link deteriorate over time?
Yes and no;
The wire will survive quite nicely, but the insulation does get hard, and sometimes brittle. But the big thing is that after so many years it may have been heat-cycled so often that the wire has become fatigued, or some strands may have come loose, or the ends are fragile.
That F-link is like a slow-blow fuse. It's job is to melt before the rest of the wiring gets hot enough to catch fire, but it takes more time to melt than a regular fuse does to blow. And over 50 years, it may or may not ,have been cycled dozens of times, there is no way of telling, except by stripping the wire and examining the strands.Unless it has obviously failed.
Two signs of obvious failure are; melted insulation, and/or separation inside the jacket when you try to pull it apart. A third sign is wire discoloration.
F-links are color-coded;the color indicates it's wire size and power-handling ability. You replace yours with a same colored one. And a same length one. They are crimped in; not soldered, then insulated and sealed.
If I can, I double crimp, the second one at 90* to the first. The quality of the crimp is very important. If you create a high-resistance connection right from the get-go, you could get stranded on the side of the road.
Do not bury it in a sheath, it needs to be air-cooled.
I know; rules, rules, and more stinking rules........
