My Raymarine 6001 Smart Pilot will hold a course but when I press either the +10 or -10 it starts the turn but just keeps turning.
Any Ideas what the problem is?
Sounds like the controller is dropping into Standby mode when you press the +/-10 buttons. If so, I still can't offer a an explanation except a fault in the control. Have you taken your question to the Raymarine forum?
If you need to replace the 6001 controller, used 6001, 6001+, and 6002 controllers are often available on eBay.