Starting info: the 680 was a wide-track (18") commercial vacuum Royal produced from 1987 to 1990, to replace the 618. Both units had a 6 amp motor and a 6-blade (screw-on) impeller fan.
For 1990, it was superseded by the 690 which boasted a 7 amp motor and a 9-blade (slip-on) impeller fan.