Uniti 2 CD: Fault 21: CD Mech, No Comms

I have recently had the CD mechanism and servo board replaced in my 2013 Uniti 2 by an authorised dealer because it was refusing to load CDs.  When I collected the repaired device and reconnected to my system, I see "Fault 21: CD Mech, No Comms".  On returning it to the dealer, the fault was cleared by reseating one or more internal connectors.  I get it home, and again, I see the same fault.

It seems likely (because the transition from working to failed involves a short journey by car) that this is a faulty or loose connector, or a break in a cable, track or joint that is affected by vibration.  I am interested to know if this fault has been seen before and if there is a common location that fails causing this symptom.