St5000 Autopilot

[GrandC2]

I have a ST5000 Hydraulic Autopilot on my Pursuit fishing boat. I have never had any issues with this unit for the 3 years I have owned the boat. This spring when the boat was put in the water, I noticed that the Rudder Reference on the ST5000 was off by 12 degrees to the starboard. The rudder reference on my boat was at dead center and it is correct not the ST5000

I went to my manual to Dockside Rudder Calibration Procedure. I went to Set Up on the ST5000 and scrolling through the options the dockside Rudder Calibration screen never displayed. The manual says it checks for a rudder reference unit. I don't know if I have one. The boat has one but I am not sure that is what it is looking for. Anyway I need to know how to correct the rudder to center. When I hit Auto out cruising the boat starts carving hard to starboard even though the rudders are centered. It has never happened before.

Thanks in advance for any help.

Mike