How do I restore suction?

SOURCE: No suction in upright position

Check the adapters at the bottom. They're supposed to move cleanly when you lower the handle. It's pretty obvious if there's an air gap when you lower the handle, and you should hear the suction in the air gap.

And...call Dyson...their support is great!

SOURCE: beater bar on Dyson upright won't turn when handle is lowered

I have finally fixed my sister's dyson dc 15 beater bar problem. It was just 2 tiny broken wires connect to circuit board lead to the beater bar. The wires broke where they go through the black rubber gommet. You need a torx screwdriver tx 15 to remove 2 plastic covers to access the wires. When looking at the front of the vacuum, the gray covers located on the right side of the vacuum. 1 big cover with a black rubber gasket and other small gray cover is on the rotating ball area.
This my new year resolution is to warn people not to buy Dyson vacuum cleaner ( Junk) design to break down! Shame on you Dyson!!!! Save your money find good old vacuum cleaner with metal parts.

OLD IS IN NEW IS JUNK!

Happy New Year!

SOURCE: Suction loss when handle is tipped back to clean carpet

Ours did the same thing. I cleaned the filter and canister thoroughly. It needed to be cleaned, but that didn't fix the problem. I removed the plate under the carpet brush bar (three quarter-turn screws) and removed all hair, lint and threads from the rollers and brush. THEN my husband found the real problem: a piece of flexible hose running from the head into the hose (on the left side when behind the vacuum) was completely clogged. The hose will detach from the head, and you can remove debris. Once that clog was removed, the hose easily re-attaches, and we had great suction once again.

SOURCE: My dyson DC17 will not turn on unless the handle

Not sure if I can help, but I'll try. The DC17 has two motors: the vacuum motor and a separate motor for the brush bar. It is normal that the brush motor works only when the handle is pulled back in the vacuuming position - that's the way it's made. So, when you say "my DC17 won't turn on", I'm not sure if you mean the vac motor, the brush motor, or both. If the vacuum motor won't turn on, then you've got a problem I can't help you with.
As for no suction through the hose, I have to ask... are you sure your vacuum motor is working at all? Even with the hose stored away, the machine still relies on suction through that hose. If you're sure the motor is working, then either you've got a blockage that you haven't yet found (there's at least one inspection port, a sort of U tube at bottom right of machine, that you need to check), or it could be that you've got a hole in the flexible hose (which opens only when the hose is extended).
Sorry if this is a bit garbled, but I'm puzzled by your problem. If you want to come back with more details I'll try again for you!

SOURCE: noticeable loss of suction, the filter has been cleaned

Hi.

Vortex will be blocked.
Try this site for help http://dysonmanuals.llc.nu/