Didn't have to tap mine. I just found a bolt that would go through the existing hole. No biggie.
Getting the washers set up right took a bit of doing, but once I got it, it was good to go for a good many brews.
And of course it's a very good idea to find a threaded rod to replace the handle so you can run the mill with a drill instead of the handle.
+1 to all of the above, also conditioning your malt with the corona produces a much more consistent crush I have found.