I’m thinking about getting a grain mill. Hand-crank is fine as long as it can be converted to electric in the future, either with a drill motor or dedicated plug-in standalone motor. Which parts can develop looseness over time or show detrimental wear? What should I be wary of, other than signs of normal wear and tear? Any other features that are a "must have", like 3-roller over 2-roller, gap settings, etc? Thanks in advance.