Amp techs....lend me your ears.

[eschertron]

I think you should try re-soldering the boards.

be kind.

[SHORT EDDY]

Most of the gear that I've worked on has been older amps that have seen years of road use. Usually stuff like XLR jacks and large components that are poorly secured are the ones that fail. The most common source of intermittent failures HAS BEEN FOUND BY ME TO BE CRACKED SOLDER JOINTS. "It comes back on if I hit it" Is a typical "symptom" of failed solder joints. I've taken on intermittent problems that have been presented to and "repaired" by experienced professionals who charged for a "repair" and would not work on "another problem" without charging more. Verdict?...SOLDER JOINT FAILURE. If my VALID yet limited experience means nothing, I'll just shut up.
I signed up here because I have a personal friend who is a member here.
It's getting stuffy in here...
Peace.

[Jazz P Bass]

I like to give a unit back that works.
Alright, you repaired 'why' the unit came in.
The unit is already apart.
It costs next to nothing to give everything the eyeball.
And I agree, the external connectors are the most likely to go next.
Reflow time is not that long compared to having to take the thing apart again.

[Ronsonic]

The blanket resolder is often valid. Depends on the product and the fault. If the box says "Crate" then everything in it needs to be resoldered. If it's a Fender Delluxe or Deville series you need to do the control section and the big stuff.

Most of these products go through a wave soldering process that tends to skimp on joints on large components (they suck up a lot of heat) and components on the edge of the boards. Look at the controls .... the faston connectors to the power transformer.

A lot of the gear we see has a mounted speaker in the same box as the electronics. It is there to shake our electronics apart.

[Jazz P Bass]

Kadoo's to that.
Nice post Ronsonic!