I have a 1990 Nissan P/U, about 182K, and the speedometer just suddenly started "sticking" today. It wasn't a gradual problem: it was as perfect this morning as it was 15 years ago, bouncing up and down as I sped up or slowed down, but this afternoon the needle has extreme difficulty matching the current speed, meaning that it very slowly moves to the current speed whether I'm accelerating or decelerating. At one complete stop it didn't drop below 15mph, but tapping hard on the front dropped it to 0. Is this something that's easy to fix?