good description Jim!
The bit I'm trying to understand is why these tails are effectively ending up "high resistance" - if they are plain copper, this can realistically only be due to corrosion in the termination or in the actual wire itself due to water ingress (when all the copper cores go black..).
Are we essentially concluding that it's down to these effects and old age?
If so then there they could be renewed with fresh terminations and similar gauge wire to maintain the 'fusible' link function..