Unfortunately I’m on travel for a couple weeks and won’t be able to troubleshoot until I return. The hum is a constant noise that does increase with volume. The amp has always had this hum since I built it and I just finally decided to do something about it. I can really only hear the hum when not playing through it. Everything does sound normal when the tone is maxxed out. It doesn’t seem like the hum is caused by anything in the environment as I have turned off computers, lights, etc. In the vicinity.
I did use a brass grounding plate and grounded the lug of the tone pot to itself (pot chassis). I believe I just left the pot to ground itself to the amp chassis as it was bolted on. I believe I also ran the input shield into the same blob of solder that is on the tone pot, if that could affect it.