Bias isn't too hard. Usually most up the cathode resistor to the EL84 pair. Usually they set it at 100 ohms/5W square cermet resistor. Blues Jr. need I think 150-180 ohm to be happy. The change is pretty straightforward. If I can gut a Valve Jr., wire it up, and not burn down an apartment, then...
Mark Hammer modded one here: https://www.diystompboxes.com/smfforum/index.php?topic=118149.0
Looks like a simple tone stack cap change and clipper change. Probably don't need much to make it the way you want it.
Okay, so the lighting isn't great and it's been super crazy around here: baseball and softball seasons
The purple is dark due to many layers of purple. The green is a nice green. The blue is my favorite, but it's been nicked up from moving (one house move and multiple storage space in said...
I love to use Duplicolor Metalcast Anodize sprays that are translucent. The colors are awesome, especially over a nicely wet sanded aluminum enclosure.
One I just did was the Rust-Oleum Imaginations(?) color shift metal flake. One of the best results painting I've ever done. Black semi-gloss...
Is there a bridge rectifier (4 diodes) that convert AC to DC? Maybe that went bad. Or is there a polarity protection diode or resistor that might drop the voltage a bit?
Just a thought for another place to check as well if the electrolytics don't solve it
I stole it off the input of a series/parallel input for a Marshall Plexi clone. Only thing is it oscillates if you have the series/parallel on and the TS switched on. I'll draw it up - have to open it to remember.