I have a question about buying a used, walk-behind mower. I'm looking at anything from 32" to 40". I do not have any experience with anything bigger than a 21", but I'm fairly knowledgeable about small engines. What should I look for and keep away from? Do I kick the tires.....! My goal is to stay debt free while building up my business. I do not have enough cash on hand to buy new. Any help greatly appreciated.