Leslie 47 loud hum

[hamoperater45]

Have a Hammond m-3 going to Leslie 47 . Loud hum at start up and slowly fades to nothing . Has been getting much worse. If I switch to on board speaker in organ very little hum ,switch to Leslie, big hum. Goes away in minute or so. Also loud pop when switching to spin Leslie . any help would be appreciated , thank you

[Jyvoipabo]

If the hum goes away in minute or so, i don't beleive it is a component failure.
Dead components rarely resurrect.

But some connections are heat sensible during warm up.

Clean tube sockets and connectors.
Move it gently, looking for sensible area.

JP

[David Anderson]

If the hum goes away in minute or so, i don't beleive it is a component failure.

There is one case with tube amps where you can get hum at turn-on that decreases as the amp warms up. If the output tubes are very old and worn, their warm-up times can change such that one tube begins to conduct before the other. This will cause hum because you're not getting cancellation of power supply ripple until both tubes are operating.

Any 47 amp should have been rebuilt by now. If it's all-original, it's a time-bomb.