Tube amp crackles help

So I got my hands on a very old, hand wired, circa-1950's tube amp that had major issues with it's circa-1950's pots (the non-conductive parts were made of wood instead of plastic! Too cool!) which I have since replaced. Now the amp sounds INCREDIBLE, however it crackles a lot even without a signal until its been on for awhile. I'm comfortable working with modern circuits and parts, but this thing has stuff in it that looks like its from another planet.

Basically I'm assuming the caps are probably not the culprit. It has the old wax and paper axial caps that hardly ever go bad. So I'm guessing it's either the tubes or the resistors. If I tap the tubes I don't get any microphonics, and the tubes look to be relatively new (definitely not 1950's tubes. They have been replaced.) So my gut is telling me its probably one or more resistors which are pretty obviously 60 years old and a whole lot cheaper to swap since I have the replacements on hand.

So before I go replacing each and every one of them, which is a ton of work due to the hand wired nature of this beast, does my plan and assumptions sound correct or am I missing something more simple to check first? Any advice from the tube amp experienced is very welcome. Thanks!

Crackling noise like you're getting can often be caused by dirt or grit in the valve sockets.

Remove each valve spraying non lubricating contact cleaner into the socket. Then insert/remove each of the valves at least five times and see does that solve the problem first.

I think you have it backwards on the caps and resistors.

It could very well be the caps. Alluminum Oxide doesnt make them invurnerable to 60+ years.

I'm surprised the thing even works with them that old. Still can at any time without proper restoration.

I would definately change out any high voltage power caps to start. This would at least safeguard the transformers which

are often irreplaceble in special design/oddball circuits.

Both Paper and Wax break down over time and heat.

Plus caps have to be gradually reenergized gradually to restore their capacitence.

Theres a ton of articloes on it. The first one I googled was here.

http://www.angelfire.com/electronic/funwithtubes/Restore_cap.html

Old tube amps also ran on 100 ~110VAC back in the day. The extra 10~20V is an added burdon to old components so be carefull.