The very earliest models of the V2000 used a motor with a different gear ratio from what is used today. Mainly though this affected ability to run at very slow speeds. I bought one of the first Venus 2000 machines and recall switching to the new motor a few years later. It made possible a much broader range of speeds. It’s possible you have an older motor. Whatever, I agree with previous poster, it’s probably caused by the motor itself. It can be switched out easily.