Hi
Just a quick update to let you know I've fixed the problem of the cones flapping about by fitting a 220V 3W Zener in the position left empty at C4.
New capacitors didn't solve the noise problem but 5 minutes after testing it the postman arrived with a pair of ECC803 S valves & it's now super quiet
.
I can now hear mains hum if I wind the amp up which was being masked by the rest of the noise previously.
I will see if I can cure that & let you know but it's tiny compared the the original problem.
In the meantime I'm off to listen to some vinyl
Regards
Damien