I know that this is off-topic, but since there are many homebrewer/designers
on this group, I will mention it. I am parting out an HP 8557A. This is the
one with the LED display.
I purchased it from a local hamfest and discovered that the sweep board had
a problem. All of the other boards, including the front panel assembly with
the attenuator should be ok.
Let me know if you are looking for any of the board/assemblies and we can
work out a reasonable price.

Pete