Hi, I've read all the other posts on this topic and learnt quite a bit, but not yet fixed the problem. The suction through the tube on my swivelling-sole-plate DC01 is barely detectable, such that one would expect a significant blockage or leak, yet I've stripped it right down and can find nothing amiss. All the vacuum channels, tube and wand are clear of debris and the rubber seals all seem good. The main head with roller picks up fine now, though that was also problematic before I stripped and cleaned. I haven't tried dismantling the cyclone itself, as I read that it is glued and not designed for dismantling, so I thought it best to seek advice first as to whether there could be a problem with the cyclone causing this. I have noticed that the dirt doesn't swirl round the collection bin as it used to, but it is certainly collecting well from the head and roller. When running the machine without the collection bin in place, suction is very strong at the tip of the central yellow nozzle of the cyclone. The other thing that puzzles me is that with the machine running and the wand in place (also with it withdrawn), there feels to be very little suction behind the twin rubber flaps/valves near the base of the tube. It was this that led me to strip it right down, expecting to find a blockage in the channels that run vertically up the back of the machine, but they are clear. I'm mystified as to why the suction is not getting through and would appreciate any advice.
Further potentially relevant info:
The tube is in excellent condition, having been replaced some years back by the firm who sold us the machine new.
The wand is very new and not a Dyson original part but appears identical to the original (we bought it online).
The rubber seal (black, not white) is in place at the socket where the tube base inserts.
I've replaced for good measure the twin rubber flaps/valve near the base of the tube with the ones you've just supplied.
One further thought: it's an old machine and has had its fair share of knocks and collisions, so the 'bodywork' is no longer 100%. I'm pretty sure the damage is only cosmetic (eg plastic arch over one of the wheels, broken strut on the cradle of the base-plate) but I wonder if it's possible something has fractured internally, which I didn't notice when I stripped it down. If this is possible, where should I double-check?