I left it for a while, thinking it might be a cut out due to overheating and would restart, but after a day, it was still dead.
I've had this Dyson for over 10 years and its been pretty good, have repaired a few things and replaced the odd part, but its still in good shape.
I sort of assumed that if the motor had failed this was akin to the engine in a car and likely to be expensive to repair, so was pondering getting a new cleaner. However looking on ebay I found that replacement motors were about £16, so not much at all.
So I got one, and also figure I needed a new filter for the motor. this is the purple and white filter unit which fits below the dirt container, and is accessed via a hatch. The old filter was black with what I assume was fine carbon dust, perhaps from the motor brushes ?
Before I started I watched this video on YouTube, which is excellent and clearly shows the complete strip down sequence to get to the motor. I did take a few pictures, but I'm not a great photographer and this clip is far better.
The only additional things I did were :
1) While the clutch mechanism was out I sprayed the belts with Platanclene Print Roller restorer. I've used this a number of times to restore old or hardened rubber. I simply sprayed the platenclene on the two belts still attached to the clutch, and fed each belt through a rag to wipe off any excess and dirt. Both belts left black marks on the rag so I assume this worked
2) I also wiped each rubber coupling seal with a damp cloth and then with a bit of platanclene. The idea was to make them a bit more supple and hence provide a better seal
3) I stripped and cleaned thoroughly the entire cyclone chamber as a fair amount of dirt had accumulated in here and I figured it compromised the suction.
4) I wiped the lower filter chamber with a damp cloth to remove the soot or carbon from it.
5) I installed a new lower filter and also replaced the yellow and blue sponge upper filter at the same time.
As per the video I reversed the procedure to reassemble the Dyson and all is fine. The new motor was not a Dyson Branded part, but did appear to have the same manufacturers name (YDK) as the one I removed.
The Dyson now works well, and seems to be collecting more dust, judging by how full it was after a house wide vacuum. Its a bit quieter too I think, but this is hard to judge. Anyway, it was a good deal cheaper than buying a new one.