I’m got one of these on the bench now.
It appears to be the same version.
The circuit board appears to read “EH 5800.” Pot date codes: 7407 and 7418 (1974)
At max CW, the rate control goes into audio frequencies for a ring mod type sound.
There is a small zone of rate control where it sounds quasi-normal, save for the lopsided/asymmetrical sweep.
The lower speeds don’t seem to be working.
The “COLOR” switch puts it into vibrato mode (pitch bending).

It appears to have a replacement trim pot, and definitely has a very odd replacement quad op amp… someone has put two SIP op amps onto some perfboard and fit that contraption over the DIP footprint.

A full trace of the pedal is on my to do list.