General Music GEM RealPiano Pro 1 Repair

I was given a General Music Pro 1 that the owner said needed a repair. The Demo will play but the keybed is unresponsive. All connections look good. I do need to replace the R output phono terminal as it is broken/cracked. Any ideas how I should start troubleshooting the issue? Thanks.

Also, the GEM power supply that came with it is rated at 15-20V DC 1200mA. Over the power terminal of the keyboard, it says 12V. Keyboard definitely needs at least 17V + to power on.