Need help with 1670 F plotter



I have a 1670F, internal antenna.

Using the default map, i drive my boat and see my track as normal, as i get to the edge of the map you would expect the map to move in the same direction as you do - right. My other units do. Anyway what happens is i drive off the map. The map does not keep up with my vessel icon.

Any ideas as to what needs to be turned off or on or what i am failing to do?

I have been working at this for days and even called Furuno and spoke to someone there and no help.
Use the roto-key and select CENTER. Then don't use the cursor (which will take the center/boat locking off) then move the boat and see what it does. If you do move the cursor to browse, hit CENTER again to re lock the boat to the center of the screen.
too late for me to try this evening i'll give it a go in the morning and report back.