Rainedupon, Rayco can supply a new wheel-or any competent machine shop could turn one out. Other than the wheel and shaft, the frame, the handelbar and the beltguards everything on that machine is a standard industrial part. Buy bearings and belts from a bearing supply house. The Kohler engine can be replaced with another Kohler -or any other small engine you wish (but if you change output shaft sizes and hole pattern on the block you will have to modify guards and obtain a new pulley to fit the different shaft.) To maintain or refurbish old stump grinders and chippers you need a set of wrenches, a welder, an industrial supply source and, (rarely) a local machine shop.