Hi Duane
Gosh, I remember those, really takes me back, I so wanted one. On the teenie bit of money I was earning those days, couldn't afford one. Had to settle for a chord organ instead. haahaa.
An Optigan I bought about 1975 from Monkey Wards. Had about 3 dozen disks. I didn't keep it long. But I got one for free last year, but only has one disk.
Duane