Pioneer xr-mt3 - mechanical problem - gear motor appears not to brakeproperly
 

This CD changer works fine.
Sometime the carriage mechanic gets stuck producing an annoying M-
error. You have to cycle power to get things reset and working
againg ... until next failure. It happens I would say the 20% of the
times.
Things happen always in the same way:
when the assy clamper opens and the engaged carriage is lifted to be
removed from its site, the carriage abnormally jams: the first
carriage theeth knocks and jams against the pin of the gear it is
supposed to engage with.
The reason is that the carriage gear has not stopped in the right
position the last time it ran; evidence is that if I turn that gear
backward a little (I would say less than one degree), the problem
never ever occurs.
Why is that gear sometimes overcoming its rest position?
Mechanical wear is one possibility.
But what about the carriage motor? It is the motor moving the gear and
the corresponding driver IC, a TA7291S, has four modes of operation:
CW,CCW, STOP and "BRAKE". What about "BRAKE"?! The systems lacks a
mechanical brake, so the motor is supposed to brake when driven to do
so by the driver....but it doesn't! (or at least non so effectively).
Carefully observing the last part of the carriage gear movement, when
brakes are supposed to brake.., the gear appears to stop by inertia
rather than as a result of the braking action by the motor. By acting
in this way, it is clear that sometimes it overcomes.

Any comment? Suggestions? Similar experiences?