Check warranty first, My Ryobe p252 was out of warranty, and other answers methods no joyp. I had to disassemble the drill and remove the gear housing down to the sheilded bearings around shaft. (leave ball, and roller bearings in chuck alone and in place) Once machined shaft end is exposed table clamp it, and use channel locks to turn chuck counter clockwise. If chuck ball, and roller bearings came loose, dismantle chuck from screw located inside chuck mouth to reseat.