Hoover U8147-900 WindTunnel V2 Bagless Upright has

Most bagless uprights are exposed to dirt being drawn through their motors and filtered afterwards. As a result when you see sparks the motor has generally suffered its final breath... Today's uprights often run with high RPM disposable motors where older bag type uprights used lower speed rebuildable motors.
So the short answer is you likely need an entire motor as a minimum. If the unit is a higher end model mover $200 , in great condition and less than 5 years old, take it to a Hoover service center and either buy and install a motor or have them rebuild it. But also consider this...
What most people don't realize is they spend more on high priced consumable filters for many cheap bagless vacs than they ever would spend on bags and in the end the bagless is dirty to handle and has a shorter life span. Mass merchants sell the vacs cheap because their profit is in the filters
Remember a vacuum is the hardest working appliance in your home in the toughest possible conditions
If you replace this vac do so at a pro shop and see the options they have. You will get good advice , you will spend a bit more with better results and less frustration because you will build a relationship .....and always know where to go for service.