Broken Belt Trouble and also plastic piece with spring has a broken part

try this link below
http://www.ereplacementparts.com/hoover-u6630900-windtunnel-selfpropelled-bagless-vacuum-parts-c-37315_37337_37584.html

Make sure the replacement belt was the right one/size.
Make sure the self propelled is on at the handle. If you replaced the flat belt and it still pushes hard the most common problem is a broken power drive cable or actuator arm. Put the handle down and move the power drive handle forward and backward. If it moves freely watch by the headlight for the cable to move the actuator at the base. If the cable is in tact it should move the actuator. If it is broken the actuator will not move. If the actuator is broken the piece of plastic holding the cable will let the cable slide or it may be broken off completely. Replace whichever is broken.
If the cable system is ok and the belt is correct you may have a bad powerdrive assembly. I will include links to correct replacement parts.

Actuator
http://www.vacuummedic.com/product.php?id=363

Cable
http://www.vacuummedic.com/product.php?id=362

Belt
http://www.vacuummedic.com/product.php?id=6


Good Luck!

try to dismantle the motor assembly and remove the broken plastic that connect to the belt maybe it is the one create loud noise.

HI, Thanks for contacting the FixYa team.

1. Plastic Burning Smell - This means that there is friction in a plastic part of your Dyson. The only place this will be coming from is the BrushBar. The brushbar has jammed somehow. The smell arises as the rubber belt is still trying to turn the plastic brushbar but the brushbar is not moving. To solve the problem you will need to unscrew the soleplate using a 2 pence piece, this is done by inserting the 2 pence piece into the 3 plastic screws on the underneath of the Dyson. Turn the screws a quarter anticlockwise. You can then remove the soleplate. You will probably see that there is a build up of debris by the brushbar. This is more common on The Animal version as pet hair mixed with dust gets stuck in here, especially if the machine has been used on a damp or wet surface. So clean this area out and then try manually rotating the brush bar in each direction. If you have been using the machine for too long with the burning smell then it is likely that your brushbar will be melted where the belt attaches to it. If this is the case then you will need to get a new brushbar. If the brushbar is not too damaged check that the belt has not broken. If the belt has not broken then replace the soleplate. Turn the screws a quarter in a clockwise direction. Should your belt be broken then please re-post and we will show you how to sort this. Thank you

If the brush roller stalls when it comes into contact withthe carpet, it might be that the tensioner spring has broken off. This is adesign flaw in the Eureka4870. The symptoms are: 1) brush spins until it contacts the carpet then itstalls, 2) the brush lever for setting floor/carpet is loose and lacks a firmsetting, 3) vacuum no longer has the feel of being self-propelled on carpet. Itis not very easy to repair and I don't know if a replacement tensioner iscommercially available. To fix it yourself:

1. Remove the base plate by the 3 Phillips screws.
2. Remove the brush roller and belt.
3. Remove the black accordion hose connecting the motor housing to the clear vertical riser on the side of the vacuum. Unscrew it from the riser. Then disconnect the accordion hose from its black connector that screwed into the riser. Then unscrew the Torx T-20 screw that holds the bottom of the hose into the motor base. Then draw the accordion hose out through the underside of the vacuum.
4. From the underside, remove the 3 Torx T-20 screws that hold the red top cover in place. They are located between the brush roller and the two small height adjustment wheels. The middle screw holds the height adjustment knob. The other two straddle the height adjustment knob.
5. Turn the vacuum upright and remove the red plastic cover. This is the most difficult step. Use a flat screwdriver to pry it loose in the hole where the accordion hose fed through. On the other side, where the foot operated upright release lever is, you will have to pry the red cover off. I broke the red plastic loop from here. But it still reseats OK.
6. Still upright, remove the belt tensioner by the 5 Torx T-20 screws, including the one connecting to the slotted arm (it has a wide cylinder under the head). Before removing the piece, note that there appears to be another mounting hole like the four standard mounts. This is the anchor for the spring which applies tension to the tensioner. The other anchor point for the spring has probably broken off, and the spring might be dangling loosely or even missing.
7. Remove the tensioner unit. Locate the other anchor point, which is probably a broken tab with a hole as the anchor point, broken through from the high tension of the spring. This is the aformentioned design flaw.
8. Drill a new hole near the broken tab. I drilled two, at right angles to each other. Drill small holes so as to not weaken the remaining plastic. I drilled ~1 mm. Holes should be between the two anchor points so as to not make the spring stretch longer than the original. Plus, a longer anchor point will interfere with the butting of the plastic edge when in the stretched position. If the spring is already lost then use a replacement that is ~1 inch long (total length) with hooks at each end.
9. Reassemble the tensioner device. Check the operation of the tensioner lever to ensure smooth, firm locking.
10. Reassemble the red plastic cover (3 screws including the height adjustment knob).
11. Reassemble the accordion hose, brush roller, belt, and base plate.

It now works as good as it every did. I will next be seeking a replacement tensioner device from Eureka or a shop, since Isuspect this modification may eventually weaken and break. The plastic springanchor points are definitely a poor design by Eureka.

Remove side cover below is a small piece of red plastic with screw attatched check to make sure belt is not broken or for some reason come off. Could be hair build up or your vaccum cleaner is not picking up enough dirt and debri causing it to clog. Steve

I'm fairly upset with Bissell over this issue and considering switching to a better brand after constantly having to replace this item on every vacuum of theirs I've had. It is shocking that they would have a part that gets stomped by your foot and jerked with the entire weight of the vacuum made out of cheap plastic. The curved piece acts like a spring to hold the vacuum upright. Can you imagine a curved leaf spring made out of plastic?? In any case, they call this an "internal part" and therefore not user serviceable. You have to call their 800 number to get a dealer local to you, usually a sewing and vacuum place, and then get them to sell you the part. Otherwise, you are going to have to take the vacuum to them and have the dealer replace it.

well, i post an answer in the wrong field, and i can't find it, so i will type one more time.
slide two vinyl side pieces off, and remove top halves. remove two screws from the switch, and remove it from top halve. between switch and outside button is a plastic rocker, which is broken. you will find two broken pieces, one spring for the rocker piece, and one small plastic rod, which goes inside of the spring for support. i do not know if part is available, but you can for quick fix like me, turn the switch on by the hand, assemble unit, and plug in, and plug out from the wall. whay? i dont have electrolux store close by.
john

Check your brush. It is likely that the brush is broken and will not spin. Hold the brush by the end caps and spin the brush and if it will not spin freely that is your issue.

You will have to replace the brush roll, part #60844-5, belt # 61120B. You should be able to get them from a repair shop, get the right one or it won't work right. You maybe able to go eureka.com and order direct.