Scott,
I think your right, it was the mixing of an accordian sound with an organ sound. I remember it being a tremelo, whirly sound. And yes, the accordian Cordovax, needed no squeezing, correct ?

My facts might not be correct, but I believe Moog bought out Cordovox in the '70's and made a Cordovox Keyboard.

Maybe others know more, but that's the sound I'm trying to edit on the 7000.

Thanks
Larry Hawk