We are a factory that makes sleeping bags filled with goose down using older Kirby Classic, Heritage, and Traditional motors. I have four filling stations running 40 hours a week with kirby motors rigged with a foot switch. All day long they are running on high speed and being clicked off and on for at least 8 hours per day monday through friday. They work perfectly and last for at least a decade or two simply by cleaning and replacing brushes or bearings every few years. Cannot imagine getting that much life out of many other things, except the Juki DDL sewing machines we use, those last a long time too.
