From here:

Here we go:

Bright cap to be removed.

Two caps in parallel to the back of the board for easier access(easier to remove if the owner desires to). We removed the small one during testing. The other might end up being removed to by its owner.

Tone cut. Replace the original resistor with sockets to try different values. We went with 150K.

Plate resistor. Added a 120K 1/2w in series with the 100k(adding to 220K).

That’s all. We also reduced the gain of the reverb driver to help tame it a little bit.