Hohner Bass 3 Synth Repair - Left 14 Keys Dead

I picked up a Hohner Bass 3 bass synthesizer recently. The left 14 keys are dead, but the right 16 keys work great with all the functions. I’ve opened the synth up and cleaned it, and I’ve tried an alternate power supply. Neither improved things. I saw no obvious issues when I opened it up and checked things out on the board. I poked around at a couple things with a Fluke and didn’t find any issues.

Anybody have any ideas on what I should check or what I could try? I’ve seen posts about dead keys, but this is half the keyboard in sequence, so I thought maybe it’s more than that. Any suggestions are appreciated. Schematic is attached or linked I believe…