Hi! I'd like to assist with this problem. First, try lightly applying a good penetrating oil, down the chuck drill bit grips alongside the bit. As you may not want to damage the cover on the chuck, the use of a strap wrench is preferrable. Otherwise, vice grips or a vise with a cloth protective wrap around the chuck should suffice. Lock the chuck into your strap wrench or vice and try reversing in short bursts. Use caution as this procedure can twist your wrists. Make sure that the drill is locked in direct drive and NOT in variable torque. If you hear clicking while trying to turn, it is in the variable torque mode and your drill will not release the grips.