This usually happens if there's debris in the chuck or it was tightened without a bit fully seated. First, make sure the tool is safe.
- Place the forward/reverse button in the lock-off position or remove the battery pack entirely.
- Grasp the chuck collar firmly and rotate it counterclockwise (lefty-loosey) by hand. Don't use other tools to force it, as that can damage the mechanism.
- If it won't budge, try tapping the side of the chuck collar lightly with a rubber mallet while applying rotational pressure.
IF THAT DIDN'T WORK: Inspect the hex end of the bit or accessory. The chuck only accepts 1/4" (6.35 mm) hex accessories and 1" bit tips. A damaged or oversized bit can jam it. If the chuck is visibly damaged or the collar doesn't rotate smoothly, the tool needs service.
HEADS UP: Before changing accessories, always lock the tool off or remove the battery. It's a key safety step to prevent accidental starting.