You need to disconnect the drive shaft at the rear. Here's a couple of TM illustrations to help. Remove cap screw #15 in 4 places - these bolts go through the rotor. Remove the cotter pin #13 and the "castle" nut to remove the cam and other stuff to clean it up and make sure everything is free. As you remove everything, you can pretty much figure out how it works. When you reassemble everything the coarse brake adjustment is made with the castle nut against the cam. You will probably be getting a brake kit, so make sure all the springs are replaced and in the right place. The pads dragging on the rotor will really wear it and make it warp badly. Oh, and make sure you back off the adjustment on the handle for the parking brake. It might be bottomed out from trying to keep up with the wear on the pads and rotor. If I remember, when I replaced mine, the rotor and pad kit wasn't too expensive.