Installed a 3-prong cord, replaced the electrolytic caps, added screen grid stoppers on the 6V6s, fixed the non-working tone stack, and adjusted the bias setting.
The owner also wanted more power out of the amp -these Princeton non-Reverbs are very clean and not too loud.
I increased the phase inverter and preamp voltage a tad to drive the power tubes harder, bootstrapped the cathodyne phase inverter for more output, and slightly reduced the negative feedback. Finally, I reduced the bias just a tad on the preamps for a little more gain.
I hate to hack any vintage amp, but these modifications are easily reversible and the owner has the few original parts I removed.
