How to put on a belt on eureka uno bagless vacuum cleaner

Unplug the vacuum.

Turn it over so you have access to the bottom of the unit (you should see the brushroll)

At the base where the "head" attaches to the body there is a small silver button that you must depress to remove it from the body. Press the button in with a screwdriver or unsharpened pencil while pulling the "head" away from the body.

Use a #2 Philips screwdriver to remove all the large screws from the bottom. They are all the same size and type so you can collect them for safekeeping without worrying about which one goes where. There are 2 smaller screws (if I remember correctly) that are for the upright lock that you do not need to remove. They will be on the small plastic piece near where the bottom brush "head" attaches to the vacuum.

Remove the clear plastic clog cover.

Gently pry the gray cover off. This shouldn't be too difficult as the cover goes loose when you remove the screws.

Flip the gray side over and you should see the innards including the brushroll, the motor, wiring, etc. Facing the assembly like you were looking head-on at the vacuum the belt should be on the right.

Pull up the far end (non-belted end) of the brushroll and then the belted end.

The brushroll should now be free and you should check the teeth on the belted end of the brushroll to ensure none are broken.

Remove the old belt from the motor (also toothed) and replace with new belt (a second spare would be handy to keep around and this is a good opportunity to clean up the air path).

Put toothed end of belt into the belt loop and stretch it a bit to get the toothed end back into place. The belt should auto adjust but just in case you may want to manually rotate the brushroll a few times after replacing the far end (non-toothed end)

Repeat the rest of it in reverse order to put it back.

Good luck!

Here is a link to replacement Eureka Uno belts and to the Eureka Uno manual which has instructions and pictures on how to change the belt:

Eureka Uno Manual and Belts