I have a DC24 that I'm breaking for parts, and took the yolk assembly off the other day, and I'll be honest, it confused the hell out of me!
Basically, you have to strip the entire front end off the machine to pop the yolk off the pivots, unpluging cables along the way, then undo the covers on the back of the yolk and pull the wires out for the brushroll.
However, to get the black plug off the old yolk and onto the new one, the plug splits in 2, and the wires can be pulled out. Pull the wires through on their own.
Then feed the wires into the new yolk, remembering the orientation (I have a picture somewhere if you need it, but take one before you strip the plug) put the plug back together (fold the cable on itself, push the bend through the gap at the back of the plug and then pull forward to push the crimp into the hole. The crimps need to be laying a certain way, the cutout matches the housing, should become clear)
Fiddle the wires back through the yolk, put the plastic panels back on, snap it back onto the cleaner, reconnect all the wires and screws and job done!
Take your time and its not too bad. Take loads of pictures along the way, then flick back through them for re-assembly, then delete them. I have some if you want to look for reference I think. Certainly still got my yolk to find out!