OK...just had a look and indeed the connecting block for the yellow wires is looking a bit sad (burnt)...so I assume this means the reg is knackered then?
I'm going to strip them back and reconnect as suggested.
Do I still need to check that the reg is gone or do I assume its past its best and invest in a new one? And if so...which, as I have read a few things about Eletrix ones or summut?