While you wait for answers, we may have found some information which could help you.
Click here for Eureka Vacuum BeltEureka Boss Smart Vac Thermal Cutoff ?
How to fix idler clamp assembly (hardwood/carpet switch) on Eureka SmartVac?
eureka 4870B smartboss, upright vaccum?
Eureka 4870 vacuum?
how doi i repair eureka boss 4870 vacuum cleaner?
Eureka Model 4870 Motor Replacement?