Ed, I have one of these factory installed in a 2188. I have the version 6.02 microchip, which I believe to be latest one offered for this particular system. If you don't have that chip yours may operate differenlty, but as tracks and I have said, there is a fairly easy way to delete old data. Now, as to your DG questions. The DG should remain constant. If it does not it indicates loss of comunication with the GPS satellites and_or beacon tower. This could be caused by a number of things. The two most common are loss of signal strength from the source or noise interference from an alternator, electric motor or other component on the machine.
