I have a walker mc 42 model number9076454. I went to replace the drive belt on it and got a gates 6845 belt that matches the old one. I put it on and it seems way to big. The tension pulley touches the other one and it still is not tight . It seems like it could me at least 6 inches smaller. Am i doing something wrong or is the owners manual wrong. Any help would be appreciated. Thanks. Almost forgot it has the kohler 16hp engine.