Sorry, but I don't have a manual but first check your guarantee as the Dyson engineer will make a call to fix it but you may have to wait a week or two. If it’s out of guarantee extended or otherwise, here are a few tips on what to look for.
It is not too difficult to pull DC04 apart, most joints are an interference fit i.e. clipped connections as plastic is fairly malleable. Suction is paramount so if there are no blockages so start with emptying the debris out of the rubbish collector and cleaning the two filters each end of this. Be sure that you note exactly how each part is fitted for reassembly when you disassembly the machine. Take a digital photo to remind you at each stage because you will surely forget if you get interrupted. Firstly, undo anti-clock the three green screws on the bottom of the vac so that the brush roller can be exposed. Remove the roller from the drive belt and remove belt from spindle both of which are the trickiest manoeuvres other than putting them back on. Unclip the bottom U shaped pipe and be sure that it you note the procedure throughout the dismantling i.e. washers. Take off the two yellow clips that hold the roller housing in position and remove by levering with your hands only, the whole assembly. Take off one side and then the other. It is not necessary remove the transparent pipe attached-just let it dangle. If there are no large pieces of debris e.g. nails, and no blockages in these pipes you need to look closely at all air joints and try visually looking at them for possible leaks i.e. check rubber washers and that they are well seated. The main handle that carries the extending pipe comes off so check that is clear too. There are some self tapped screws, two on underneath the bottom of the dust box under the bottom filter. If the machine stops you need these out and the electric motor comes out together with a cover - remember to put the cover back over the housing before refitting. The other screw just holds an air pipe. With the motor and cover in front of you remove the top cover. Note which the red lead is attached to and mark it for reassembly. Look at the brushes to see that they've got stuck up and not touching the commutator (copper segmented circular part that the brushes touch (take out two screws on each one and lever the holder up with a screwdriver slightly and you should see the brushes are pressed out by an internal spring). At this point you can check the switch is operating satisfactorily by using a continuity test on the red wire e.g. the black wire should be connected either on or off.
Reassembly is in the reverse order which you will have either noted or photographed taking particular care not to have anything left over e.g. screws or circlips.
Reassembling the drive belt is best done by fitting it on the motor spindle first then pulling through the rubber belt and holding it with two fingers. Feed the roller through the short end to the drive space and get the belt central before placing the roller into the slots provided.
Hope this helps to save you some money if not you've lost nothing by trying and gained more experience for the next effort. Just have the confidence to pull it apart and look closely before you take off the next piece.
Best of luck.
Pete, April 2008
