So.. back in June last year I flogged a refurbished DC07 in white to my mate for 40 squids.
Fast forward to last Thursday and I arrived home to a few messages on my phone.
So I went down to his and picked up the machine. Lobbed a new (good used) motor in (Didn't have any new ready) and gave it a wipe around, and one hour later took it back to him. Offered to do the work for free because of how short a life it lasted, but his Dad really wanted to give me a tenner. Job well done for now!
The cause of the failure was the top bearing had failed miserably. I originally suspected brushes and commutator but just turned out to be the top bearing. I guess you could replace the bearing and off you go again. The price of a new motor just aint worth it!