2020 Rover Stepthru speedo freezes on a number. This happens after a few miles of riding and doesn't affect performance or odometer. It holds a number like 14.7 mph even when you slow down and speed up. Sometimes as you increase speed it goes up a few mph like 15.2 and then freezes on the new number. Is this problem the controller, hall sensor, or display PCB? Bike has 213 miles of easy use and never wet or wrecked. Anyone have similar experience?