Is this how it goes...?
You have a 5381A laid bare on your desk and then along comes a faulty 8656B that pushes its way in and occupies all the available space, demanding full attention for the rest of the day? (FYI, I think it was noticed ... standing on edge, taking over my desk for the evening. Nothing has been said ... yet.)
Some updates on the "functional" unit....
- Power on, all segments and LEDs light, fan spins up, no smoke
- Frequency, modulation and attenuation functions seem to operate from the front panel as described.
- The internal timebase output provides a 10MHz signal at about 8V RMS
- The Option 001 High Precision Timebase output provides a 10MHz signal at about 8V RMS
- The difference between in frequency between these two at about 15 minutes from power on appears to be less than 7Hz
- Modulation output provides a 1V peak signal of 400Hz or 1kHz (as selected)
- No RF output that I could detect, irrespective of settings. Edit: and what is that RF output connector?
... but the most interesting thing I did find was a strip of masking tape hidden in plain view on the underside of the unit: