Doubtful that it's programming.
I just got done fixing eight dead keys on an old metal-case ESQ-1. They were grouped in pairs spaced eight keys apart. Turns out it was a result of someone spilling coke or some other corrosive drink on the keys years ago. The PCB traces around middle C eventually ate through, killing the keys above the broken connections (the encoder scans the keys in groups of eight, which accounts for the regularity of the groupings).
If you're technically inclined and want to chance buying the ESQ, you'll have to remove the keybed by removing the ten or so screws that hold it to the metal case (they're on the bottom of the unit). Carefully lift the keybed up and out of the case, and carefully disconnect the ribbon cable, taking care to note the orientation of the connector.
Examine the key contact springs on the top three notes (the FATAR keyboards on these units used brass springs to contact the upper and lower contacts, the idea being that they would self-clean. It worked so-so). Try cleaning the springs with contact cleaner first (Deoxit works best on the oxidized brass). If this doesn't work, you'll have to do some more adventurous work...
There are small nylon holders underneath each key that hold the key contact springs. You can mess up a spring if you're not careful. I unscrew the spring holder then carefully pull it off (one at a time for 61 keys). Carefully remove the nylon holder from the spring, taking care not to over-stretch the spring. Once they are all removed, you can remove the printed circuit board by removing the screws holding it on. Remove the PCB and turn it over. Examine the PCB traces and solder joints.
If this ESQ has the same issue mine had, the PCB traces are cut between the upper three notes and the three keys 8 down from them (if I'm correct, the top three keys will correspond to the Eb, E and F keys just below them). You'll have to run three jumper wires from the back end of those three diodes to the top Bb, B and C diodes.
Let me know if you want to attempt this, and I'd be happy to help walk you through it. If not, I recommend you find a qualified tech....or a fully-operational ESQ!
regards - DY