Piano/Harpsichord sounds on Crumar orchestrator

Hi. I have an Orchestrator that’s fully functional except the piano and harpsichord sounds don’t work on 6 or 7 keys. Does someone know which circuit board needs to be replaced, and if that’s a difficult job to perform? Thank you!

Replacement boards are a non starter.

First you need to find out of the problem is mechanical or electrical.

open the synth up and look for burnt capacitors, funny smells.

Then open the unit up and see if this explains your issues.
https://forum.vintagesynth.com/viewtopic.php?t=62712

if not, then look to see if its a problem, with poor contacts with the slider pots.

If not then your looking a failed IC chips, but start with the other areas first.