I wanted to share with all a fix for the TFM-55x amplifier buzz. Rita of Sunfire deserves all the credit here, she suggested I put a 910 ohm 2 watt resistor across diodes D505 and D507 (rectifier circuit, AC side) on the side of the diodes near the orange wire that comes from transformer T1. I installed the resistor and the noise is now barely audible, it was load enough (both speakers) to render my amp unuseable. Thanks to Rita! I have a complete TFM-55x service manual with all schematics if anyone needs more detail.