[Uncle Bulgaria]

Thanks Tony. a) I have dealt with by making a new record switch (other thread in this forum). b) I haven't manually cleaned yet, apart from a bit of Servisol 10.

I wondered if there was some intermittent fault in the signal path. I've traced it back to before the volume control by ear, but as there doesn't seem to be a monitoring option I've not been able to tell if an external source has the same interference. Today I think I'll have a crack at understanding my oscilloscope...