Thanks for your reply.
Unfortunately this get's me no further. I already have the instruction booklet for the CM927. It refers to a receiver unit different to the one I have installed in the Esprit boiler.
Sorry about double copies of the photos. I am new to this system.
I wish I had bought a pair now but thought at the time it was only the transmitter that was faulty.
A full reset sounds like a plan. Can you advise please what I have to do for a full reset?
Tried it Andrew.
Still no joy