I bought this old tiller last year. I think it's from around 1976 and I believe it may have been built by MTD. The motor is a 3.5 HP vertical shaft Briggs & Stratton. The motor runs well but I've been having issues with the rotors not turning well enough to do anything any the garden. I was told that the tiller had new belts when I bought it. I was also advised not to touch the bolts on the sides of the deck (there are two on each side) as that would affect the belts. When I was checking all the bolts this spring I found that those bolts o the side of the deck were loose which caused me to wonder if the belts are loose. I've searched online and I can find any information on this tiller or how to adjust the belt so I am wondering if anyone has an idea how to adjust things so the belts tighten up. Thanks.