I've got Nav 3 that over the years has slowed right down and had difficulty spotting satellites. Now that Garmin no longer support this model, is it for the bin or are there companies out there who refurb them. It cost a grand new and I see from stuff on this forum people prefer them to Zumo 550/660. I've done a factory reset to no avail and the last time I plugged the USB in it didn't even register on Windows Explorer. Can't bear to chuck it. Any advice please