Hi there. It sounds to me like you have a worn drive belt. Go to http://www.mtdproducts.com/webapp/wcs/stores/servlet/OwnersCenterView?storeId=10500&catalogId=20500&langId=-1 enter your model numbers in the center field and download your manual. It will show how to remove and re-fit a new belt. Take the old belt with you when purchasing the new one. Hope this helps