Hi – a stairlift user here; am hoping my ignorance can be clarified by some wise souls on here! I have an older minivator unit and am wanting to replace the motor and seat only (track is fine) – can I simply purchase a secondhand unit and get it installed onto existing track? Does it matter (other than dip switches and settings) whether the unit for sale is left or right sided? Are the units built to go either side of the track or do I need to get a unit that turns the same way as mine currently does? Any advice greatly appreciated. Regards