Before I joined EEVblog, I did a repair of an Ivie Electronics IE-30A Spectrum Analyzer in 2018 on AntiqueRadios.com website:
https://antiqueradios.com/forums//viewtopic.php?p=3000319
I fumbled my way through it but found a short that kept one of the frequencies from displaying

Unfortunately, the power supply section faded away soon after even though I replaced the large rechargeable batteries. At first I bought Ni-MH ones but soon realized that I could only use the original Ni-Cad types. I'm not sure if I caused more damage because of it

Well, I packed the spectrum analyzer away for a future repair attempt.
The IE-17A is an Audio Analyzer that bolts to the bottom of the Spectrum Analyzer.
After reading its Users Manual, I found that it can send "snaphots" of graphs from the IE-30A when its connected to an oscilloscope! They even give examples of some. Extremely cool

Anywho, this is one compact little instrument:

Something that I was wondering about was, would it be possible to internally switch from a Ni-Cad charging circuit to a Ni-MH type? They mention that the demand for power is high when attaching the IE-17A. It would be nice to really beef-up the battery capacity.
But, of course, I need to see if this thing can be brought back to life again first.
I will attach all of the individual schematics, user's manuals, and calibration documents.