Sequential Circuits Prophet 5

Title link takes you to shots via this auction. Note the switches on the top right.
Details:
"Sequential Circuits Prophet 5, serial 0074 (Rev 1). There were only 182 Rev 1's made, many of which were returned to Sequential when the Rev 2 came out. Nowadays, there are probably less than a couple dozen working Rev 1 Prophet 5 keyboards in the world.

It's a fantastic sounding synthesizer - I've compared it directly with the Rev 3 (the majority of the Prophet 5's) and it's distinctly warmer and the resonance is more musical. It instantly recalls the classic soundtracks that the Rev 1 and Rev 2 keyboards were responsible for during the late 70's. It's a classy looking synthesizer as well. While there are a few scratches and marks, it's in remarkable condition considering it's 30 years old.

I had it serviced in August 2006: the battery was replaced, it was recapped, and had general maintenance performed. It's been solid ever since - I've kept it in a clean studio environment and have not gigged it. All 5 voices work, all knobs and buttons function, and all keys are responsive and extremely playable.

A previous owner modded it with 5 switches. These switches, along with the sequencer interface jacks, were disconnected at the recommendation of the service technician (they were interfering with the stability). The previous owner also added a cassette interface from a Rev 2, and it's working properly."

If anyone knows what the switches did, please comment.

Update on the mods:
"the CV/gate only control's voice 5. With this mod you can have each voice control (by the same CV/gate) .. so instead of getting a 2 OSC mono sound, you could get a 4 oscillator mono sound."