Replied to your post in the DC07 forum but if you're still stuck I have one in the garage I can whip apart picture by picture for you if it helps!
Good luck with the DC24, horrible, horrible machines to strip and re-assemble. Brushroll motor may just need the reset button pressing on the side, or the continuity of the wires checked (little panel on one side of the ball comes off with 3 screws and there's that end of the cable, or a new motor or pcb.
Since you sound like your handy with the multimeter, you should have half a chance of a good diagnosis. I got lucky with both of mine in that the brushroll was fine. Got nearly £50 for a refurbished brushroll housing! Nearly as much as their worth as a whole vacuum!