Hello, I have an old Garmin GPS 12XL that mostly works fine, except the trip odometer on the Position Page doesn't seem to be working correctly. For example, at a shown average speed of 2.5 MPH, after an hour of walking it shows 0.3 miles. Is there a setting I'm missing, or is it just old age? Batteries are fresh. TracBack on or off, no difference. Thanks for any suggestions anyone might offer. JSD