1970 swinger wiper switch and speedo

Not sure if you wanted the rallye cluster or not but here is the standard rectangular style info. Just happening to be repairing my cluster and had the speedometer out. I would test yours with a cordless drill driving the speedo cable input since they have to move a fair bit to show mileage changes.

The cable input drives a gear which drives a gear to the right and then another vertically to the odometer gears. You can take out the odometer and turn by hand to test. Just look closely at the black plates between the numbers and make sure they go back correctly. They act as stops holding the number wheels in the correct place.

My guess is you have a broken tooth on a gear and are in a dead spot. Here are some pictures to help.