ElectricEye78

I recently purchased a used M9 and everything works except for the parameter knobs. I've only been able to find one other post with this issue and it was on a modded unit so the solution was to contact the tech who did the mods. My unit doesn't appear to have been modded so that's not an option. Anyone have a similar issue and know if a solution or at least a place to start troubleshooting?