It's almost definately moisture in the capsual/element.

You could try this.....
Short out the element by bridging a wire across the two terminals of it.
Listen to the noise of the electronics only.

If the spluttering is still there that confirms it ain't in the element.

Re-solder solder joints using fresh solder....
Clean out the tube/valve socket.
Maybe replace valve...
Clean the pins on the valve with emery/sand paper etc. so they are shiney and not looking corroded...
Examine any electrolytics for leakage....replace if required .... ( though this is unlikely).....

If the noise disappears when you short out the element ,, then it must be the element....
In which case i suggest you leaving it outside in the sun between 5 and 10 minutes ........
Don't cook your gear. :lol:

Hope this helps.

8)

That's a brilliant idea! This sounds the same as the sputtering caused by moisture, but I've tried everything and the sputtering had gone away, but it just returned and i can't imagine how. Having said all that, this capsule is hyper sensitive to humidity (if I breath near the mic it starts to misbehave).

I'll try that shorting idea first.

I really appreciate your help 8-)

John

The capsule has three wires coming from it. There's one from the centre of each diaphragm, and another from the body of the capsule itself. Should I connect the capsule wires to the one from the capsule body?

BTW when I remove the grilles the hum is very high, so I hope that won't stop me listening to the electronics.

I really appreciate your help :D

Thanks
John

I've connected the centre of each capsule to the body. All I can hear is valve hiss, with a very mild hum. Actually, there's less hum than when the capsule is working!

This is very reassuring. I was certain that I had done everything possible to get rid of capsule moisture, but I'll just have to try harder!

Thanks again :D

John