I found that my old ST6 is not as accurate as it once was.  It was not
too bad if you let if warm up for a while but off somewhat when cold.
I am talking about the accuracy from note to note and not absolute
pitch which the internal calibration does.  This is the factory
calibration done by adding capacitors for every note.  You can check
this by using a audio oscillator and a frequency counter.

A year ago or so I found a newer Conn ST11 which has a digital divider.

Bob Wilson - Electronic Organ Service
Decatur, AL