Not much can be done as the chuck is not specifically designed to handle hammer drill operations (they crack the scroll thread adjuster inside ) best get a new chuck and if you do a lot of hammering get a proper hammer drill that has a push in operation not an ordinary electrical drill with a hammer capability
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WD 40 sprayed on the movable parts usually will free it up. So will penetrating oil.
Not much can be done as the chuck is not specifically designed to handle hammer drill operations (they crack the scroll thread adjuster inside )
best get a new chuck and if you do a lot of hammering get a proper hammer drill that has a push in operation not an ordinary electrical drill with a hammer capability