[C320-list] Raymarine Autopilot failure

[Ben Waltuck]

The autopilot is one of my favorite toys on the boat since it allows me 
to move around and play with my other toys on the boat.
(raymarine st6000 wheel drive)
I was out for a sail this morning, and my autopilot will not turn to the 
right.
I can engage the unit, and it will make steering corrections to the 
left, but never turns the wheel back clockwise, so I eventually get far 
enough off course that it alarms.
Given that it does turn left and is aware of going off-course, it seems 
that the control unit is good and the drive unit is bad.

Do the drive motors have a limited lifespan?  I ask because West Marine 
sells a replacement motor drive:
http://www.westmarine.com/webapp/wcs/stores/servlet/product/10001/-1/10001/68043/10001/734/628/3
Has anyone else had their motor burn out, and did it burn out in one 
direction only?
Is this the kind of thing worth sending to raymarine for out-of-warranty 
repair?  A new drive unit is $500, so replacing it wouldn't be the end 
of the world, and I'd rather not be without the unit for several weeks 
while they fix it..

What's most puzzling to me is that there are 2 wires that connect to the 
motor drive unit on the wheel.. so I assume that it's just reverse 
polarity to turn different directions.  Based on that assumption, it 
makes no sense to me how a motor can function in direction but not the 
other.
With the power to the unit off, I can engage the unit and spin it both 
ways against the friction of the motor.. so I think I've ruled out a 
mechanical blockage.

Has anyone had the drive unit fail on their autopilot, and did it fail 
in only one direction?

I did get the "low batt" error message once when I was far off course, 
so I'm wondering if that means that it was "trying" to turn right..

Any advice would be greatly appreciated..

Thanks