via this auction
"This ARP Odyssey is, as you see, the first whiteface version** which is by far the most desirable. Having the legendary, extreme, and unique sounding 4023 filter. It has had at least a couple major servicings and highly desirable mods. First, from CMS who are FAR AND AWAY the leaders in working on these ARP systems. The CV/Gate mods were installed so that this can be controlled by other synths, and the External Audio Input so that other instruments can be run through the filter. The second major servicing and mod was performed by another very prominent tech in the vintage synth community. This mod I think is very unique among Odysseys that you will see. ARP has the duo-phonic feature that will assign the two oscillators to the highest and lowest note you play. Which is great. Sometimes, however, you want to treat it as a monosynth, and with your playing style it’s a little bit of a pain that it triggers the two notes. This switch disables the two-note tracking/assignment and lets it play as a true monosynth. 
In both of these services, electronic rehab and tuning were done, and complete disassembly and cleaning of the sliders. It has had another tune/checkup done about a year ago, which included replacement of some of the sliders. The sliders move freely and are not stiff, but frankly you can hear a little scratch again on some of them. I am also going to claim that, after shipping, you should plan to tune it again. But other than that it is in excellent shape electronically. Cosmetically, it’s a solid 9 out of 10 if not 9.5, with a few marks that are tiny, small places the silkscreen is fading, etc.Other functional aspects, the key action is good, as are the two-position switches. The octave selector is supposed to do +/- 0, 1, or 2 octaves up or down. The détente-ing is a little flaky so it really only does normal and one up, one down. HOWEVER, I am providing a NOS (NEW OLD STOCK) extra octave selector switch with this auction. It seems to work well flipping it with your fingers, but I can’t guarantee the result when you install it. Again, it has never been used!
Other extras include a plastic fitted see through dust cover, custom made for this Odyssey. This is awesome to have because you need a dust cover to keep the sliders from getting junk in them, yet in your studio you want the synths to be visible when you’re hanging out, not buried under opaque covers. Finally, the synth comes with a medium duty flight case."
