Seals but won't draw all the air out. Seals fine

There are belts in the clutch that lose elasticity and need replaced every couple years. If they are loose and slip the brush roll won't spin fast enough to clean carpets properly

Perhaps the bags you are using are not suitable. If they are too thin it will not vacuum air out.

Hi Jo, it's Jack at Dyson.

DC33 offers a high level of filtration, and the issue of dirt escaping from around the seals between parts would be very unusual. It's possible your machine has been damaged in some way, or that some parts are not correctly assembled.

To help you resolve this we would need to take some additional details, and to talk you through some simple troubleshooting checks when you have your machine easily to hand. If a repair or a replacement part is needed, we'll also be able to confirm whether this is covered under the free Dyson parts and labour guarantee.

When convenient, please give the Dyson Customer Helpline a call on 1-866-693-9766 (US), 1-877-397-6622 (CA) 1800 239 766 (AU), or 0800 298 0298 (UK).

We'll look forward to speaking with you.

John, as you know air flow and CFM of the air is what makes the vacuum work. There is rubber seals or gaskets all along the air way to keep the air moving from the floor through the vacuum motor. You need to be sure a gasket has not wore out and allowing the vacuum air to escape. The vacuum motor must have a place exhaust the used vacuum and that pathway also has seals to insure it leaves the machine at the place the engineer who designed the machine wanted to go. Check for worn seals/gaskets in both incoming and outgoing airways. D&R Services, Inc.

you are not using a "good" bag. Make sure there are no holes and that the bottom and sides of the bag are properly sealed. It will run all day and not pull the air out if the seal is broken anywhere.

Please remove the recovery tank and check and see there is a black rubber ring seal on the large vacuum tube that rises from the base to meet the bottom corner of the recovery tank. This rubber seal may have fallen off the tube and be found laying under the hood. It seals the vacuum source to the recovery tank.

You need to check the seals. It is loosing prime after one stroke. I had the same problem and found obstructions causing a seal to leak and allowing air into the sytem. Take it completely apart and clean thouroughly.Also do you have the dial to choose between carpet and tools? If so make sure its not on the tool setting. I have done this numerous times only to find out i forgot to change it back

When you remove the dirty water tank, on the machine, there is a screen that gets clogged and will prevent good suction, is this one clean? If it is, do you feel suction at that screen, if so then there is a problem with the tank. If no suction there, then you will have to check it over for a air leak or a bad seal.

Try eBay or you're local plumbing/bathroom store.  What you need are called o-rings.
My problem was that there's an o-ring on a spike in the hose attachment and that was split which meant it leaked water/steam.  I replaced it and it's working fine again.  I got my o-ring (in a pack of 200 assorted sizes) from eBay for about £3 but that was only because I was too lazy to go down to my local plumbing/bathroom shop which probably would have sold me 1 for a few pence.  Much better than £50 to replace the hose!