
See also
electric drill.
Stiff, hard to turn. Remove rust with steel wool and liquid rust-remover. Then oil at all points that move.
Chuck stiff, doesn't hold bits tight. Unscrew to the left until the sleeve comes off. Clean jaws with liquid rust-remover and oil. Replace as you found them and screw back sleeve.
Bit dull, cutting edges bent. Place in a vise and sharpen with a small triangular metal file. Be careful not to flatten the bit on the outside.