I don't know about ft William, but Stoddart in oban (an hours tow?) are the local yamaha dealer. I've only had brief experiences but they were positive.
A1an very kindly came over this evening for a look at it. We think it's an electrical/sensor fault.
It'll need the diagnostic software to find the fault.
I can't thank A1an enough for having a look at it for me. A true gent.