You'd like to think the conductor's strands are separated and fluxed before being carefully set into a mold where piping hot lead is poured in for a 100% air-free connection.
The truth is only some of that care is taken and there's room for corrosion to form.
A pal was driven bats**t because his truck was running so very badly. It turned out an additional wire was included in the positive cable's swag to power the "computer". The corrosion severely interrupted current flow.
That cable was 24 years old.
It might pay to cut the old clamp off and add your own. We've all seen tired lead clamps just break with time and stress too.
Do you have enough slack?