Raymarine autopilot - stops giving rudder to one side

[UAT Norway]

I have a linear autopilot without rudder sensor, that after about 10-15 minutes indicate full rudder to port or starboard. This causes the autopilot to stop giving rudder to that side. This could happen to both sides. The pilot steers well until this happens. I have not noticed anything wrong with the compass heading.
The setup is a Type 1 linear autopilot on the rudder stem, Smartpilot X10 and ST70 panel.
Any thoughts?

[Yngmar]

If it worked before without a rudder position sensor and now it doesn't, then the drive might be slipping. I'd be inclined to take it off and have a look inside and see if the belt (#16) is in need of replacing.

[UAT Norway]

I have opened the unit. The clutch and and belt looks fine.

[Yngmar]

Test it under load and see if there's slippage anywhere.

Without the rudder position sensor, the autopilot simply counts how long it went left and how long it went right. If those don't add up because the drive is slipping, you get exactly the symptoms you have, where it loses track of the real rudder position because it's not where it expects it to be.

You can also add a RPS, but unless the problem is NOT the drive, that won't solve the issue.

[marioxp]

Unfortunately, I also have a problem with the autopilot. The autopilot is similar if not the same but has a rudder position sensor.
I removed the rudder, until then it worked, after that it doesn't anymore and the display does not show that the rudder is moving, the dashes are always in the middle.
When removing the rudder, we loosened four allen screws, and one cable (so that it could reach the screw), on those two semicircles. We did not touch the autopilot or the rudder position sensor. We put everything back the way it was.

I don't know what could be the cause? Does anyone have any advice on what to pay attention to.

Next time I'm on board I'll take pictures, I don't have anything right now.

[Yngmar]

the display does not show that the rudder is moving, the dashes are always in the middle

That means the rudder position sensor isn't working. Totally different problem, as OP doesn't have a RPS.