During the refurbishing process no component is overlooked.  Belts are replaced, ignition, injection and other mechanical parts are reviewed, adjusted and/or replaced.  Parts that are known to be failure prone and are worn, or any parts that are showing serious wear are discarded.  Some items may be replaced with used parts, but only sound units are installed.  Wear items like brakes, belts, hoses and filters are always replaced with new parts.  Where practical, some items are upgraded to heavier duty replacements.