I have seen many DC24's especially on ebay that have had brushroll motor failure, and these small motors are usually only available as a complete head assembly. Its a good thing that most Dysons now come with a 5 year guarantee so at least you can own it for 5 years with no financial outlay for its repairs, as Dyson are actually good at repairing them under warranty. But A vacuum for the price asked for a Dyson should be expected to last longer than 5 years in a domestic situation.
Of all the Dyson DC07's I bought to refurbish and sell on again, the most common problems were motor's arcing or burnt out completely, plastics snapped off, main hoses that have rips or tears in them, broken handle retaining lugs on the back of the switch housings, plastic soleplates that crack, break or disintegrate, and on the clutchless models, broken brushroll belts and brushroll clatter. But many of these problems were caused by owner neglect to maintain the machine properly. Bagless machines are much more prone to motor failure through overheating, as people dont clean the filters as often as they should or operate the machine with uncleared blockages.
One of the biggest problems on the DC04, was the mains cable breaking internally at the joint to the spine of the cleaner, at the switch housing grommet. Also, the wand handle wasnt reversible as on the DC07, so that the handle iself got in the way of using the wand. The DC01, was a nuiscance for having to buy new pre motor filters as they werent washable, and it didnt have clutch control for the brushroll. It also had relatively poor suction. The other big problem with the DC01 was that the top of the handle often suffered from broken plastics where the tools fitted into the end of it.