Hi Daniel,
I'm dealing with the same issue on a Kurzweil K2500. I suspect it's power supply and want to ensure that the correct components are in place and that all the voltages are good. If you could share the manual and schematics with me too, I'd be very grateful. I notice you are quite active on the Korg MS2000 group as well, I've posted a bit about DSP repairs on that.
If the power supply is the same as the K2000 then it will be simple enough to get that info.
Sometimes thought the devil is in the detail and if there are upgrades to handle more current then the correct schematic and service manual would be critical.
Thank you...!