Vintage Synth Repair

Wondering if anyone might have ideas on this:

A Drumtraks I've inherited works fine [all sounds trigger, etc] except there is no kick drum. I've tried triggering with midi as well as the pads and re-seated the eeprom but no dice. Of course all the other sounds use a different size eeprom so I can't swap eeproms to see whether that is the cause. 

anyone run into something similar or have a schematic they might want to share?

many thanks
steve