I am an original TAM owner and can attest to the buzzing happening on brand new units. I received a replacement TAM with bose, same buzzing. Swapped just the bose bass unit, then just the TAM, the problem always returned. Again, brand new units direct from Apple. So I look at recapping advice...
For anyone continuing to work on TAMs I recently did an upgrade with an IDE to SSD adapter and a 128 GB SSD. I bought the parts on amazon. I took out the IDE drive, used an IDE to USB adapter to connect the drive to a G4 mac mini running 10.4 Server and OS 9, (the mini itself using an SSD card)...