Electro-Harmonix EH 8000 early 80s

I originally acquired this unit in the early 80s, and was told that it was a prototype from Electro Harmonix that hadn't gone into production, and there are so few of them in existence I tend to believe this. I haven't plugged it in for 40 years, but as I recall the tone-tracking electronics were pretty basic, and it tended to have a hard time tracking the fundamental if other strings were resonating. The exterior has some minor scratching from having been stored in cable crates for years, and a couple of the slider pots need to be replaced. I haven't plugged it in to see if it works, but I believe that the rarity of this item overshadows its functionality. There are schematics available online, so any repairs would probably be pretty straightforward.

***Update: I recently plugged this in to see if it still works, and it powers up and outputs both the synth and raw guitar signals. All three oscillators are functioning. The tracking works about as well as it did in the early 80s, which wasn't great. Perhaps with some aggressive compression it'll track better. But it still does surprisingly well after 43 years! Was unable to engage the filter section, but that may be from my unfamiliarity with the signal flow.