Just wasted an hour testing the double rectifier.
No response on "goodness" test for either rectifier.
Had an untested EZ81 knocking around and no reading on that either , semed
unlikely . The owner tried out this amp and some amplification, but
unuseable, for other noises and soon switched off.
As EZ80 / 81 uses the same socket as ECC81/82 unlikely a wiring problem
there and expected to have to dive into the big bakelite multiway thumbwheel
switch bank.
Just about to try 2x 1N4007 in the socket and thought I'd check the Avo, 9
digit code from first principles. My 1968 Avo valve data book for EZ80 and
81 has setting code
7*1 23* 6**
(for amplifier anodes , not diode anodes) but it should be
8*1 23* 9**
in this particular case
801 230 900