Just amazing work, dmeek, as usual.   

Do you have freeze spray in your arsenal?  Can be very handy for finding iffy transistors, killing warts, etc.   
But I do agree with dmeek, sounds like an intermittent connection or relay.

Also keep in mind that whether electronics, engines, etc., some times things sound the best right before they explode.   
It's best to know the theory first, safe operating parameters, datasheet recommendations (application notes), and then play around within those safe areas with listening tests.
Usually, compromises are made, in terms of tone vs reliability.

Biasing by ear will not get you anywhere unless you can always duplicate the same signal level you biased with.
Transistors are usually biased to be in the most linear part of their operating range, to allow the widest variation of signal level.

Schematic attached.
In the unlikely event that the tank turns out to be ok, make sure D15 at tank input is not shorted.

Quote from: Wattsup on June 25, 2025, 12:35:09 AMCan you insert images directly on to a post here or does it require an external hosting site?

Click on the "preview" button and you should be given the option for attachments.

Sorry but I don't have any other info regarding these amps.  I didn't find anything online either.  The schematics came up in a repair related thread.

At least the B/W version is based on the Vermona Regent 100-G1.  That is the only one I found info for (from other threads on this forum).
Owners manual and schematic attached, you will have to check and see how far the schematic differs from the blue-silver version.

All your faults are typical pot/jack cleaning and re-soldering issues.  None of them indicate any faulty caps.
I doubt doing a re-cap will increase the value of the amp, meaning I expect you will get the same money for it either way.  For an amp you are not going to keep, it is a fair bit of extra work, with potential for creating issues, but that's just my opinion and I don't mean to discourage you.

Why do you want to replace all those caps?
Internet commandments about shotgunning electrolytics 'while you're in there' is most often just bad advice.  It sounds like the amp is generally working ok with no major hum issues.  Unnecessary repairs/parts replacement quite often creates new problems, especially for beginners.  Traces are delicate and can be broken, wires and cables can be damaged from just flipping the board over.  Solder bridges or poor solder joints, etc.
 
If this is not 'replace all electrolytics' but rather a targeted selection of caps, can you post the schematic and list the schematic designations for the caps to be replaced?

As far as other things to look at, I would be more concerned about bad solder connections.  Vibration and heat cycling can loosen up solder joints, especially around heavier components, or things doing physical work, like pots and jacks.
When these amps were current, and we worked on many of them, you would get to know which joints would commonly go bad, and just re-solder them as routine maintenance.

Since it was not blowing fuses, you can put the output transistors back in.
Like DrGonz said, voltage checks are the best way to proceed.

Since it has an output cap, it will be AC causing the hum, not DC on output.
You can disconnect the speaker if the hum is too annoying, and measure the AC volts at the output.

Schematic available here:  https://www.ssguitar.com/index.php?msg=16694

It might be more obvious without adjusting supply while testing.  Just set for 24VDC and turn on. 
Some are not very loud, put your finger on it and you might feel the click.

1/4 or 1/2 watt in carbon film or metal film will be fine.
Check the dimensions, some of the modern parts are so tiny they can be difficult to work with in applications like this.

Quote from: Rkskaas on June 09, 2025, 08:24:03 PMI am getting 1.3v between TR4, TR5 base pins

How about resistance?

The one across D5 you should add in also.  You can see on the issue2 schematic it refers to the same note as R74, so it would have been added at the same time.