While you wait for answers, we may have found some information which could help you.
Click here for Changing Belt ChangeHow to fix idler clamp assembly (hardwood/carpet switch) on Eureka SmartVac?
Eureka Boss Smart Vac Thermal Cutoff ?
how doi i repair eureka boss 4870 vacuum cleaner?
Eureka "boss" #5893 stops sucking after 10mins?
Eureka Model 4870 Motor Replacement?
Eureka 4870 vacuum?