Hi Clifford,
This I noticed on Tony's car on Saturday as well.
Yes, it's probably an earth connection but it could be anywhere.
I suggest you first thoroughly clean the 2 earth 'spiders' at each side, removing them as well
to clean the back side, then check all the wires. You may well find that, although the
crimps look ok, one or more are at fault. Fit new connectors and see if that helps.
Also, the light clusters themselves may have faults too.
Nigel