Alec wrote:

I used to be a service engineer for 17 years for a Cyrus dealer in
Gateshead and there were very few problems with Cyrus 2's, the paint
came off the knobs and most of the problems were caused by the input
selector switch causing either 1 or 2 channels going off. From memory
I believe the 3.15amp fuses were the + and - supply rail fuses. Is it
off on all inputs ? and have you done the usual swappy around things ?

Thanks for replying.

Yup, the paint came off the knobs years ago ;-)

I've done the swappy around thing and it's happening on all inputs.
Jiggling the right speaker output seems to cause an intermittent signal
which suggests to me some sort of loose connection at the output socket?