Yes I saw those two relays on the circuit board. In theory I could jumper the contacts of the suspect relay to diagnose that the relay has failed, but which contacts to jump would be guesswork on my part, not a good idea.

No I don't have access to another switch unit. That would make things far too easy lol.

I am going to proceed on an assumption that the relay has failed (in one direction) and just keep my eyes peeled for another drivers side switch panel.

Thanks for your input Alterastro.