[PJL]

This is without the lamp limiter? The voltage readings look better matched now. I expect you didn't leave them long enough to fully warm up as the sum of the currents is different depending on the socket they are placed in.

The caps need to be replaced as if they were going to recover they would have done that by now. The entire power for the output stage passes through these capacitors so again we need something with a ripple current rating of at least 300mA.

It looks like F&T have stopped their range of low value dual can high ripple current capacitors. These should be OK:
RS: 739-4582 Nichicon CA series UCA2W100MHD 10uF 450V 105degC

Decca must have been trying to save metal as cramming the electrolytics in such a small space under the chassis does not look too clever. The elevated temperatures would have reduced performance and shortened life. The one I have proposed is 105degC which will help.

Our posts crossed: I agree, it looks like the valves will be OK. Those caps need changing before it is safe to put it in the cabinet, then a further check as the HT will have changed, a soak for a few hours, final measurements and then it should be done. Any other ideas on a source of electrolytics? I would check and replace any out of tolerance resistors (well actually I would probably replace the lot rather than waste time checking them) - what do you think?