$20 on ebay got me one of these
Brian Instruments Brikon 723 Floppy Drive Analyzer
Ever since I’ve seen this device mentioned in the datasheet of many different floppy drives, I knew I wanted to get ahold of one. There are some disreputable companies selling refurbished versions of this unit for $800 or $900.
Mine does need cleaned up, but it appears to work ok.
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This thing is a monster. It’s about 25 pounds. And has a heavy duty oscilloscope-like handle on the front, as you can see. I have to take it apart and clean it up.
But I really need a manual for this thing. I’ve figured out some stuff, but could really use a manual.