I have a pair of 99D's. I have gone through
these amps. I replaced some bad coupling caps and a quad filter cap
with a new one. I don't trust the NOS quad ones that look the same. Caps can
die on the shelf. The new one is of close enough value and new. I
cleaned and lubricated all switches and pots. I have tested them on an
oscilloscope into an 8 ohm resistor and they perform to spec. I have
included screen shots. More photos at the below address.
NO TUBES! I borrowed some to test these. I may have some please ask if you are interested. Missing one fuse holder, I may have one, they are common and one bottom cover.
You can get the description of the scope capture by putting your mouse over it.