I was recently reading an article on Crimp Lugs used in electrical installations and apparently this particular problem is the most common cause of cable/connector failure, next to using the wrong sized connector.
Looks like this particular crimp lug has just corroded and burned away because of the higher resistance connection.
![[Linked Image]](https://www.electrical-contractor.net/ubb/frown.gif)
This could have been a nasty failure had it gone un-noticed.