Can you take a pic of the outside bottom showing the hole ?? Try to get close without blurring the pic and maybe we can tell if it was done when the pot was made or added later !! I really see nothing unusual about the pot and without it being marked it would be difficult to tell where it is from !! And remember,, back in the sixties ( I remember that decade well ) $10. was a lot of money !! So value then and value now might not be what you expect !!