U6634900 won't shut off

SOURCE: Hoover Bagless Windtunnel - Self Propel feature not working

I have the same problem with ours. If you lift the vacuum by the handle it breaks the lever on the transmission. You can find a replacement cable and lever on line for about $16.00 it is somewhat involved to repair but can be done by someone with mechanical ability. You can try and find a repair shop but be careful, they sometimes tell you the part is not available and try to sell you something else. I think they should be able to do the job for aprox. $80.00, but they may want more. I did it myself plus the height adj. knob for $24.00

SOURCE: Decreased suction at hose end

Yes, the "door" on the angle hose might not closing properly when the vacuum is in the upright position (if you look at the vacuum from the back, this hose connects the back to the bottom of the vacuum and it has a "door" at the very bottom end that is supposed to block suction to the lower part of the vacuum while upright) Check for a build up of linty stuff in the corner. The best way to access this is to remove the two screws on the clamp found at the top of the hose, (freeing the hose on top only), straighten hose so you can see inside to the end, and watch inside as you press the upright release lever. (awkward, but worth the effort) You should be able to see the door move -it should be completely open when the vacuum is not locked upright, and should be completely closed when upright. Remove anything that might be preventing it from closing - I used a flathead screwdriver. Hope this helps someone!!!!

SOURCE: Hoover Bagless WindTunnel vacuum cleaner.

very easy. you have clog. take the brush off look where the hole is thats where the clog is. it might be in there you might have to take the housing off of the motor

SOURCE: hoover windtunnel bagless - won't turn off

BRUSH WON'T TURN ONE

SOURCE: Hoover U5780-900 Windtunnel Cyclonic Bagless

You probably need to change the belts. Here are the belts you need and the manual:

Hoover 5780-900 Belts

Manual

Testimonial: "Replaced the belts-- works GREAT!!! Thanks"