i use a butter knife, just take some pliers and pull the removal tabs apart so you can get the butter knive in. then push em apart enough to get the disc in. how did you take the calipers apart? like totaly? you may need to re-bleed them/have them re-bled. every time i have one of my wheels off my retard brother comes up and starts squeezing the levers like crazy, its like he is attracted to em or something .