This usually means debris is stuck in the chuck jaws, or the chuck itself is worn.
Let's try to fix it step-by-step:
- Open the chuck jaws as wide as they go.
- Use a can of compressed air or a small brush to clean out any sawdust or metal shavings from between the jaws.
- Look inside the chuck for any damaged or missing teeth.
- Insert a bit, then tighten the chuck by hand as firmly as you can. Don't use the drill's motor to tighten it.
- Give the chuck a firm tap with the heel of your hand to seat it.
If that didn't work: The chuck mechanism might be faulty. Try a different bit to rule out a worn bit shank. If a known-good bit also slips, the chuck needs replacement.
Heads up: A slipping chuck is a safety hazard. If cleaning doesn't solve it, stop using the drill. Chuck replacement is a common repair covered under warranty if the tool is within the 3-year period and registered.