I have a B&W 51SB-B sideband generator which I use with a 5100-B
transmitter. The generator worked fine until recently, when output from
the grid circuit disappeared. I discovered a faulty resistor and
replaced it, plus I replaced the two 1N34 diodes, which are nearing 50
years old and, I am told, don't age well.

The result: Grid current is up--although it seems to fade on 10
meters--but the output meter indicates far less output than before.
Also, the grid current goes below zero while the B-plus is on, but the
unit is not being modulated (i.e. I'm ot talking). This is an old
problem and I don't know what's causing it. I'm not sure I should worry
about the output, since the unit seems to work and the transmitter
output appears normal.

Is there anybody out there who is thoroughly familiar with these
sideband generators and can answer a few questions?

Thanks in advance for whatever help you can provide.

Steve, W3DEF