We have a Raymarine ST4000+ autopilot on Molia. This was not working reliably last season.
To get to the autopilot, we first had to remove the wheel. Once the wheel is off, the autopilot wheel drive unit unplugs.
The instructions say to replace the drive belt if is damaged.
Having removed the support plate from over the clutch rollers (2 screws), we saw that our belt had a loose string, and there was lots of fluff in the drive – we have ordered a new belt!
Work in progress…