[7T9Shark]

Thanks for your help. I tried to attach the photo of that other switch I was talking about, but I think it's a mute point now that the trouble has been found.

You saved me tons of time, sanity and money.

snorander - if you're reading this, your help was much appreciated, too, as it put me on the path to the switch in the first place.

Cheers,

A. J.