Tube amp noise at start up

[kydave19]

I bought a Fender Tweed Blues Junior IV Ltd Edition brand new a few years ago. Never left the house and rarely played.

Recently fired it up and there was a lot of crackle, then verged on feedback, then went quiet and played normally.

I'm cycling it a few times, letting it cool, the restarting. Can I expect the crackling to diminish with more frequent use?

It is very quiet (as to extraneous noise) and sounds great as soon as the start up trauma passes.

Per suggestions, I have carefully pulled out & reinstalled each tube & I have run all the knobs back & forth multiple times.
More detail. After about 3 - 4 seconds of crackle, a feedback loop starts and crescendos in another 5-10 seconds, then quiet and the amp works normally with no background noise. Any idea on the feedback? I've made sure I had the amp freestanding and not backed up against a wall or corner.

All the above happens with ALL the knobs at usual settings (mid range) OR zero'd out at turn on.

[Bubbalou]

Sounds like your tube sockets need retentioning (using a thin sharp probe to close off the tube socket pin receptors). The fact you hear crackling until it warms up indicates the pin tube receptors are spread open to far and with heat making better contact when the amp heats up.

[phantomman]

My money's on a marginal solder joint on the PCB or a ribbon connector that's partially unseated.