a towel dispenser includes a housing , a sensor , and a motor assembly that causes in response to a hand : a leading edge of the toweling to be extended from the housing a multiple of a predetermined unit length , optionally plus a further extent that is less than pul ; and then to be retracted . the motor assembly ceases retracting based on sensing the leading edge of the toweling . pul is set in a length learn sequence by : retracting the toweling until a leading edge of the toweling is sensed ; advancing the toweling a preset extended length greater than at least a distance between immediately adjacent lines of perforations in the toweling ; retracting the toweling until a leading edge of the toweling is sensed while measuring a length by which the toweling is retracted ; and determining the difference between the preset extended length and the measured retracted length .