Black keys less responsive than white keys on minilogue

Hi everyone,
I have a korg minilogue which requires the black keys to be pressed much harder to initiate a note than the white keys. I dug into it and the unplugged the connector cable from the keys and main board and reseated it nice and tight. That didn’t help. I also checked the connectivity between all the points in the cable and looked at the contacts under the keys for corrosion and dirt. Everything looked good.
Any idea what problem might target the black keys and spare the white ones?
Should I give everything a bath in contact cleaner?
Thanks for any insight.