My vacuum will not engage to unlock to vacuum. I turn the vacuum on - that works fine. I put my foot on the part to make it so I can vacuum and it will not unlock. What could be the problem. SOO frustrating!

We are Fixya, we aren't Hoover. You need to contact them direct or take it to a local Vacuum Cleaner repair shop.

There are parts schematics in this link. Parts 30 and 31.

https://www.google.com/search?q=hoover+uh30301+parts+schematic

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Depends on what you mean by 'disconnected the lower part.'

See end of the note for a link to the manual. Dyson doesn't have it directly, and a number of places either want you to download spamware, or only have a non-english copy.

1) If you took the roller all the way out, you will have had to have eased it out of the loop for the drive band, and then eased it back through after cleaning. If it's not through the loop, no drive power. The band is stiff, so it can be a bit of a challenge to pull out far enough to get the roller back through. Use a smooth dowel or other smooth sided lever to pull band out enough to feed the roller back through. (Smooth = not cutting the band)
2) If you didn't take the roller out as in (1), or did feed it back through the belt before closing it all up, then there's a couple of possibilities. A) The brush will not spin if the unit is full-upright. Put your foot on the lower assembly, pull the handle back to the 'I'm about to vacuum something' position, and try again.
B) According to the manual, this model has an 'engage brush' button. The system should start with the brush engaged, but try toggling it with the handle not up-right.

If still not spinning, turn off and unplug. Try spinning the brush by hand. If it spins freely, the clutch to engage the brush isn't engaged. If there is resistance, then it's engaged (unsure if it auto-disengages when powered off. You's want the handle tilted back when you try this).
Manual Link:
http://homeappliance.manualsonline.com/manuals/mfg/dyson/dc18.html

Good luck!

I have one of these LE models also. Yes, the on/off button is broken. I have had to replace it twice on mine. My local vacuum repair shop suggested NOT to use your foot to operate this switch, but just press it on or off with your fingers. That will help to keep it from breaking.

I definitely can help you out here but need to know, what make / model vacuum are you referring to in your question here? It just shows "vacuum" as the item...

Please let me know, just reply to my answer here and I can help.

Thanks,
Tim

I don't believe that these vacuums have a belt so the only thing that I can recommend is to unplug it, turn it over and see if there is anything obstructing the roller brush such as string, tinsel, rocks, etc. See if you can turn it with your hand without using much force. Good luck!

The easy answer to this problem is you need a new cord. Any fit all 20 to 35 foot two wire cord will work. However, you will need to take disassemble the almost the entire vacuum to test the current cord to see if it is bad. There are a lot of pieces to take off to get to the inside of the vacuum where the cord enters from the back. You could also have a bad motor.

The roller is likely jammed, or there is debris around the belt area

Check your clutch to make sure it's engaged. There should be a knob on the foot of the vacuum that can be turned to stop the roller.

S3765-040, power head would not run when the handle was elevated. Problem was with wiring from connecter plug on power head swivel into the power head itself, because of the design the wire tends to develop a short. Test it by turning on the vacuum, elevate the handle, then when it stops running move the visible part of the wiring with you foot/hand. If it starts/stops then you have a short. Replacement part was about $10.