65 Fender Twin Reissue crackles at high volume

[booj]

By high volume I mean with the chassis in the cabinet and a guitar signal turned up just to the point of distortion (LOUD). The crackle happens on the loudest part of the note played and may snap a half dozen times, always with the same intensity and sound. It does not happen with the chassis out of the cabinet.
I have re-flowed the solder on the control board and the main board. I have also swapped out the output transformer with a known good one. My next idea is to re-flow the solder on all the tube sockets and replace all the lug type connectors with soldered connections. If that doesn't do it then I'll replace the speaker cable and the wires to the speakers. My question is, has anyone else had a similar problem and know what fixed it?

[The Dude]

It's possible you have an intermittent connection inside a tube. Try tube substitution and see if that takes care of it.

[booj]

tried new output tubes. No luck. Not sure if all the preamp tubes have been replaced. I've taken this on for another tech who doesn't have time for it (like I do!) Ha!

[TimmyP1955]

Check all ground screws/nuts. "Exercise" all Molex and Faston connections.

[lowell]

Worth checking DC on power tube grids. Recently fixed an amp with this problem and the grids were reading very different negative bias voltages. The negative bias voltage was fine where the grid leak resistors met. Replaced the leaky coupling caps and fixed it.

[booj]

Problem fixed. took out ALL lug connectors and soldered the wires directly to the lugs. Left the ribbon cables alone