While running corn with new-to-me S660, the corner post indicators for both the header tilt and height will bounce around erratically much of the time.  They read solid when sitting idle, but seems the vibration of running causes a loose connection somewhere.  Occasionally they drop completely off, which gets really annoying with code beeps and recording function disengaging.   

Any advice on which plug or harness is the likely culprit?  The issue always affects both readings at the same time.  TIA