The most common salt mill malfunction is clogging. This is caused by moisture in either the salt or the grinding mechanisms. Moisture can enter a salt mill when it's placed in liquid or used over steam. Fortunately, clogging is easy to fix or prevent.
Open up the mill. Discard the contents.
Clean the mill and grinding mechanisms with a small dry brush. Wipe the body of the mill with rubbing alcohol. Air dry all parts for at least 24 hours.
Add dry rock or sea salt to the salt mill. Include a few grains of rice to absorb any moisture.
Lubricate the threaded part of the mill, lightly using cooking oil and fingers. Prevent salt corrosion and increase the ease of assembly.
Adjust for the desired coarseness of salt by tightening or loosening the screw that connects to the grinding mechanism. Reassemble the mill. Test by turning the grinder knob.
Store the salt mill in a cool, dry place.