If the fault occurs mainly when printing multiple pages and
the drum maintenance shaft seems to behave in exactly the
same way whether or not a fault is flagged, the problem may
be related to a buildup of commutator brush material on,in
and around the y-axis (drum) motor and its leads.
In other words, the motor might be shorting the power supply
and the fault displayed is just a coincidence (the y-axis
motor spins up the drum just after an oiling cycle is
completed when printing multiple pages).
I'm not entirely sure of the diagnosis at this point, but
we were plagued by this problem and it seemed to disappear
for a while after moving one of the wires leading to the
the process or y-axis motors. Cleaning the y-axis motor
and its leads seems to have solved it (time will tell).
We had already replaced the maintenance drawer so the
lift pins were in good shape and were not the cause.
Taking the motor apart, by the way, is easy.