Couple of point :
I have 2 6th editions.
Oldest copy has the 12-2 error in 23 says C then straight line- as mentioned
newest copy has a sticker over 23 and 24 and the change to 23 is A then top arc and straight line- transposition of the error. I got it new that way- anyone else see this??
Bummer.
Times two!
What to do?
Just take matters into your own hand -- the pen and your knowledge of truth! -- and make the appropriate changes.