Jazz P. Bass:  I included the voltages on the .jpg and .pdf attached here this time (I must have attached them incorrectly last post) and exactly where the measurements were taken.

Basically:
At the +-22VDC point, the measured voltage was +-20.3VDC.
At the +-37VDC point, the measured voltage was +-68.2VDC.

Upstream of that, the transformer secondary windings were as follows:
Lower voltage taps were 17.4VAC and 34.7VAC.
Higher voltage taps were 27.5VAC and 54.6VAC.

I'm guessing that the 68.2V is an issue but am not experienced in how to troubleshoot further.  Thoughts???

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What is important is the follwing 4 voltages.
+22Vdc
-22Vdc
+37Vdc
-37Vdc
These are the rectified dc voltages that the amp needs to function properly.
Please list them.

I finally got to taking some voltage readings.

g1: Mentioned getting the voltages might uncover issues.  Below is an image of voltages taken at various points.  Would anyone have suggestions based on this?

5V 1Khz signal is way too much.  50mV would be a better level.
But for DC static voltages you do not want to be applying any signal at all.
Recheck DC at Q8 and Q0 with no signal applied.  And check the pinout, it looks like you have the emitter and collector readings reversed.

Update

So, I have been tweaking the circuit for the past couple of days and I think I've got it where I like it. Actually, there are a few versions that I'm fond of, so I'm going to make it a switchable two or three-channel preamp. Honestly, this design has enormous potential, afaic. I haven't tried it on 18V yet. That's still on my to-do list.
Now I'm going to need a nice clean channel to pair with it. Any suggestions are welcome.

Is it OK to post a schematic with my changes? On his site, Joe Davisson put the 'do not copy / all rights reserved' clause, so I wouldn't like to infringe his copyrights, annoy him or anything like that, hence my question.

Hi, joecool85.
Sorry about not posting the schematic or link. I should have done it in my first post. My bad.
Actually, it's this one
https://www.diystompboxes.com/analogalchemy/sch/v4preamp.html
The one you provided shows the 3-stage bjt Vulcan overdrive pedal and they sound completely different.
As for the diodes, I used 1N4148.

For those looking for the link to the schematic: https://www.diystompboxes.com/analogalchemy/sch/vulcan.html

I'm curious what the diodes are for between the stages though.  Not sure I've seen that before.

Another thing to try would be a patch cord connecting FX send to FX return jacks.

Quote from: g1 on May 27, 2024, 01:54:20 PM

Quote from: Frank75 on May 27, 2024, 08:18:36 AMAs soon as I moved the volume pot I lost, say, 80% power.

Have you cleaned the pots?  If not, do so. 
If you already have cleaned them, it sounds like the volume pot is defective or needs to be re-soldered.

A dirty pot was my first thought too so I did give it quite a few twists and turns. No crackles, no pops, no jump scares.
Potfluff doesn't seem consistent with losing volume over time. Strange though that moving the pot seemed to trigger the defect, so not excluding any options at this time. Including coincidence 

Quote from: Frank75 on May 27, 2024, 08:18:36 AMAs soon as I moved the volume pot I lost, say, 80% power.

Have you cleaned the pots?  If not, do so. 
If you already have cleaned them, it sounds like the volume pot is defective or needs to be re-soldered.