Transformer Buzz

[gjoyce3]

I have had my Kaiju up and running for a month or so and have enjoyed building and listening. Unfortunately, my unit is buzzing more that I think acceptable - easily heard from my seat - about eight feet from the amp. The hum/buzz is definitely at the unit and does not vary when adjusting the trim potentiometers. Per the advice in other threads, I savagely tightened down the screws on the power transformer which did not have a perceptible impact. Thoughts as to where I should look next?

Thanks in advance.