Set of Replacement Balls for the Standard 4mm Chuck
A set of replacement chuck ball size 9/16” (14,29mm).
Replacing balls is typically a temporary solution to a worn out chuck.
They will usually improve the runout for a short time.
Ultimately you will need to replace the chuck itself because the ramps these balls move through are what is worn.
These ramps cannot be “reworked” and achieve the necessary precision so the only solution is to replace the entire chuck assembly.