If you have the exact model Eureka that this repair was listed under, model 4388 then please find a link to the belt you need below. If you'd like to verify the model number, please check the back or the bottom of the vacuum for a sticker that also will contain the serial number, and look for the word Model Number. If you don't have the 4388, please just add a comment with the model you have and I'll be more then happy to verify these two models take the same belt, or give you a link to the belt that goes to your model if they are different.
Here's a link to the exact belt called for on the model 4388:
Eureka Extended Life Style U Belt, Part 61120
Here's step by step instructions on how to replace the belt:
How To Replace Brush Roll Belt
NOTE: Turn off the switch and unplug the electrical cord
before replacing belt. Belt pulleys can become
hot during normal use. To prevent injury, avoid
touching the motor pulley when checking the belt.
1. Lower handle to floor to change belt.
2. Loosen, but do not remove, two screws to release hood.
Lift hood to remove.
3. Lift left end of brush roll.
4. Remove and discard belt.
5. Place new belt around motor pulley.
6. Place belt around brush roll pulley.
7. Align left end cap with square in base. Push
end cap into place; see left side view.
8. Pull right side of brush roll to stretch belt.
Secure right end cap into base.
9. Rotate brush roll to seat belt.
10. Replace the hood. Make sure hood front is
behind furniture guard. Hood should seat
onto self-locating screw tabs.
11. Tighten screws.
I hope this information was helpful to you in changing the belt. If you have any questions about how to change this belt, please just add a comment here on the repair page of Fixya, and I'll be happy to answer any follow up questions you might have. If you found this helpful, please be so kind and rate my repair helpful and / or leave feedback for me.
Thanks so much,