1000-point score reel doesn't always advance properly

The 1000h point score reel doesn't always advance enough times, or at all. The game always seems to chime the right number of times, but the score reel can skip. If it happens on when the reel is on a 9, then the 10,000-point reel can advance while the 1000-point reel stays on the 9, so you get an extra 9000 points.