With about 2,500 miles on the clock, I installed a Ford 140 mph speedo on my Mustang GT. The "new" speedometer shows just under 96,000 miles now. Recently the trip odometer has started malfunctioning. It works OK until it rolls over from 99.9 to 100, then the numbers get garbled and it stops working. Are the mechanical trip odometers repairable? Anyone done that?