I would'nt fear non-use sitting in a shed. As long as it wasn't sitting in standing water, should be ok. THere could be bearing problems due to previous field use. Are the fluted meters all rusted up ? That would tell me what moisture conditions may have been present during this storage time. Some rust would be natural, excessive rust could mean some more indepth examination to assure fewer breakdowns during field use. If it sells cheap - I'd consider it a good buy . ...