Found this elsewhere. I had same problem and Dyson sent me out a new cyclone. Best if you try John's fix first which should do the job. Just cleared out top of ours again, got piles of dust
Cross-post follows:
Dyson DC07 loss of suction - this may help!!?
Hi everyone.
I had this problem with my DC07 and found the top of the cyclone was stuffed full of compacted dust.
You can (should be able to ) see all way to the top if you look up through the bottom of the center column. If ther's a load of dust up there, you should be able to dislodge a lot with a cane and a good shake.
I actually got to the point where I had nothing to loose, so I actually took the very top plate off the cyclone (3 or 4 Torx screws) and saw a huge plug of dust.
Do please note: Getting the top off and back on again is a **real bugger** because of the unlatching mechanism.
Having proved that Dysons **do** clog, I phoned Dyson and got hold of someone technical.
I described as briefly and concisely as I could the problem - top of the cyclone full of dust - and pointed (politely) out that Dyson's advertising stated clearly the machine was supposed never to clog. Ever.
I made no attempt to disguise the fact that my vacuum was out of warranty.
Dyson simply sent me a new cyclone and dust can free of charge!!!
I have a small dentist's style mirror and had a look through the hole at the back of the cyclone assembly, where the cyclone assembly connects to the suction port on the vacuum main body.
If you squint through this hole, you can see the 1/2 inch nozzles on the bottom of a couple of individual cyclones.
The old assembly had a bar across each nozzle. I think the bar was at a slight pitch - like a stationary airscrew - to make the air swirl as it went up.
The new cyclone assembly had no bar, but I thought I could see some spiral grooves in the bore of the holes instead, which should have been enough to start a swirl.
So, it looks like there was a design change in the cyclones at some point (could it be that the old ones tended to clog?).
The vacuum is now back in business and sucks like a Turkish masseuse.
Hope this helps a few people.
John
February 2008
George, March 2008
