I have a 1987 troy built Horse with 7 HP Tecumseh Engine with serial number 844351, but I can't find model number to get pdf for service manual. Can you help? Everywhere I turn they ask for a model number, and I would like to know that too, but I can't find it. The serial number is on the right side of the housing in line with the wheels where the handles attach to the top of the frame. Herb