Hello everyone. I have a Furuno model 1815 that I have a question about. On the top of my display screen it says hdg. I assume this is heading but I don't see how to access it or use it. It is filled with stars. Also I installed my unit myself and didn't realize that the apparent that the magnetron stays on even though the display unit is turned off. Mine shows $6,300 hours which is roughly when I installed it over 200 days ago. Does this mean that my magnetron is past its life. Thank you in advance