How Do I Replace A "Permanent" Belt On Dirt Devil Model # 091210?

It is not really Permanent....once you take off the bottom by removing the 5 screws you will see the gear that come out from the motor and there is just enough space on the left side to slide the old belt out sideways and to slide the new belt in.... But I am getting ahead of myself....unplug the vacuum and lower the handle...turn the vacuum over so you see the bottom of the "works"...then remove the screws to take the bottom off. Lift the roller out and you will have slack on the belt...take the roller out and set it aside. Using your fingers, carefully turn the old belt sideways and remove it through the space....as I said above. To put in the new belt, keep the "teeth" of the belt towards the inside and slide it carefully sideways through the space.....mesh the teeth into the gear coming out of the motor....hold the belt open and put the roller back through it so the teeth line up with the gear on the left side of the roller....pull the roller gently toward you so the ends of the roller fits back into the slots...the roller should turn easily. Replace the cover with the 5 screws....