We received this Sanitaire SC679 Commercial Upright Vacuum instead of the SC679J. I don't know how it got mixed up, but evidently this is an earlier model. The vacuum has worked well, but removing and replacing the roller and belt for cleaning proved to be an hours long process, trying to fit the roller back in properly. There are no videos on youtube and no direction on the Net to tell how to do this. I decided to write out directions for those who have this vacuum and wish to keep it. We find it works great for our needs. The directions for other maintenance on the machine matches with the SC679J directions Sanitaire SC679 roller replacementTo work on the roller, place the handle as far down as it will go, then turn the machine upside down.1. First open the metal plate, slipping back the latches. Make sure they are flipped back when replacing the metal plate later.2. Look very carefully at how and where the roller is placed in the machine, and also how the belt is situated. The shorter side of the roller from the belt groove is on the left.3. Take off the belt. You can take a screwdriver and place it under the belt and use two hands to stretch it off the pulley.4. Look carefully again at how the roller is placed. The protruding square tabs should be pointing up. The long sides slide down into the slot… with the square tabs up.5. Pull out the roller… and pull the belt off of the roller.6. Examine the roller. It may have hair wrapped around it. To remove the hair, cut it loose. You can use a sewing thread cutter, and a long nosed, slanted pair of tweezers.7. Once the hair has been cut off of the roller, pull the rubber caps off of the ends of the roller. You can use a small flat bladed screwdriver to start doing that.8. Next look at the grooves in the end of the roller and remove the hair from there, using the same tools as before.9. When the roller is completely clean, put the caps back on, and put the belt back over the roller.10. Then replace the roller. Make sure the belt groove is closer to the left hand side. Slide the roller back into the grooves in the machine. With it positioned correctly, it will go in easily. Tabs up, long sides of the hex end into the slots.11. Once the roller is situated, run the belt up so it goes from the under side of the roller, up in the pathway of the groove in the housing of the vacuum. You can use a screwdriver again to stretch the belt back over the pulley.11. Then put the cover over the roller, putting the tabs into the slots and pulling the latches back over the cover.12. The vacuum roller should now work much better, and the machine should vacuum much better..I hope these directions cut down on the learning curve to maintain this vacuum.