Good question.
But hard to answer. I guess just run your radio for a while and see if there is any fluctuation. If you are game enough to change the 6M5 socket, Jaycar have them in stock.

Personally, I would get rid of the socket, they are easy to come by new and if you can get a ceramic one all the better.

OP tubes & Rectifiers run the hottest. With my 132L I fitted a three wire cable. The AWA 92X on the repair bench, has already been retrofitted as I had to repair the transformer.

The unit should run better if you got rid of all of the out of spec resistors & leaky paper caps. Leaking caps can impinge on the bias of the valves, this leakage, especially if positive, is capable of stopping the radio.

Marc

I already swapped out all the paper and old electrolytic caps, only the micas are original up to now.

MORE SYMPTOMS

This morning at cold start the radio ran at lower volume than when switched off last night. After about 45mins it suddenly snapped back to higher volume. There was also some burbling distortion of lower frequencies, like an overloaded speaker.

Could this all be socket issue or should I be looking at other components - like the remaining mica caps?

Maven

When I get a problem like this I usually turn the receiver on when it is cold and gently tap and wiggle any valves in suspect sockets and see if this causes interruptions. Given that you have replaced all large capacity condensers (micas are usually in the pico or nanofarad range) a valve or valve socket may be at fault. All valves with top caps and bakelite bases contain soldered joints and manufacturers spat them out like machine gun bullets. One of these soldered joints could be dry and you won't see it until some method of detection is employed.

If you suspect a socket, change that first. New ones at Jaycar are only a few bob. If the problem persists I would try swapping the set's valves with known-good ones of the same type and see if that cures the problem. if you are short on suitable valves, try the valves from the set you are working on in another set known to work and that uses those valves.

It might be a dry joint? Probe around with a chopstick.

That is also what I would expect of a Silver Mica and the 132L had to have several replaced.

If it is not changing frequency, I would be looking at any SM with high DC voltage on it, and / or associated with the AGC

I assumed the papers had been gotten rid of. that normally improves performance.

Marc