slip an eight or ten mm ring spanner over the clip which holds the cable in the back of the drum. If you use the right size it holds all the clips in and you just pull on the cable and it all comes out.
I've seen a couple of people having trouble getting them out and this way makes it SO easy! I must have had a brain spasm or something when i was doing it cos it was the first way i tried and Im not normally that smart LOL