Jeff, it could be as simple a fix as Harold suggested below however it could be worn or missing parts causing the snowthrower to not stop properly. First you need to know if your 128 has the PTO brake on it or if it the older style without the brake? The changeover to the brake version happened during the 1x8/9 series, which your 128 is from. Here's some photos from a service manual to help you determine which version you have.