I'm not a true TruTrak expert, but here is an explanation that might add something to the discussion:  The TruTrak servos are "stepper motors," distinctly different in operation from the servo motors used in other autopilots.  The armature is essentially a collection of permanent magnets and the stator creates a magnetic field that attracts the magnets.  This field is the "stepped" around the armature by energizing different coils in succession, and the armature follows in phase with these steps.  That's why the stick can be observed to move in distinct steps, presumably small enough to avoid it being obvious.  Instead of providing a slip clutch to allow the pilot to overcome the servo (on other autopilots, you do routinely test the clutch by overpowering the autopilot don't you?  You don't?  You should) TruTrak limited the torque capacity of the motor and this can be programmed.  Set the autopilot and then overcome it by moving the stick - you can feel it "pop" loose and then grab again.  Set the torque capacity so that the force to overcome is significant, but not so much that you would have trouble flying the plane that way, at least until you can reach over and shut off the power to the A/P.

In flight,  the servo produces a distinct characteristic if it is overloaded and slips.  Sort like walking uphill on ice - it progressively moves in the commanded direction until the opposing force is too high.  When the motor slips out of synchronization it loses it ability to produce torque (and slides downhill).  Then when the force drops sufficiently it gets back into step and tries again.  It pushes and trips, pushes and trips; a characteristic not at all like simple "hunting," which is smooth and proportional in both directions.  If, set at the highest torque, it still is overloaded in normal maneuvers, you need a higher torque servo.  However, in roll you have no clue as to the force imparted by the trim, and the plane will fly just fine in an out-of-trim condition - the servo doesn't care how much torque it takes to move until it is more than its capability.  If it won't bank or level off  you might want to first check to make sure it isn't out of trim before blaming the servo.

Finally, the shear pin:  It is there to protect against the possibility of a mechanically locked servo motor.  Note that, unlike the "others," the TruTrak servo is never disconnected.  The controller simply turns off power you when hand-flying and you simply back-drive the servo motor.  If the motor physically jams and won't turn (like from a broken tooth in the gear-train) the fix is to apply enough force with the stick to shear the pin.  The pin was never intended to shear in any other circumstance.  So if your pin shears without a jammed servo, something is amiss and needs to be fixed.  Replacing it with a stronger pin isn't what I would recommend, as you may not be able to shear it if you have to.  A jammed control that can't be overcome is THE worst-case scenario.

For what it's worth

Gary Casey