Hi again. There have been a number of posts here describing how to check if it is the mast-head gear
or the instrument. With the power on the voltage will vary as described by one:
"You may want to call Raymarine technical support to doublecheck, but this is what they told me when I had a similar problem:
Measure voltage at the back of the display. If the values are:
o Between Silver and Red around 8V
o Between Silver and Blue 2-6V
o Between Silver and Green 2-6V BUT DIFFERENT THAN SILVER AND BLUE
o Between Silver and Yellow 0-5V
then the masthead assembly is OK and it is the display that is faulty. "
(the colours refer to the connectors)
You may need to search the forum and www for more??
Here is one which describes how to replace the bearings.
Raymarine wind speed slowing down