good day everyone 
  my 6in round circles are not round
 there are 2 flat spots  one on each side of the circle  at 3,30 to 4 o clock  and 180 % out 930 to 10 o'clock. 
both flat spot are about 1.5 long inches  the same . 
 this where i guess.    I'm thinking it is backlash  and its OK if I'm thinking wrong  
 i am reading my manual as i am writing this. 
   if this is a backlash adjustment  how do i know which axis to set or have a problem with.  I'm at 1511 units per inch 
   is there troubleshooting manual or a book that i can get or  buy, download. 
  it is hard to keep on asking questions I'm sure the answer is in my manual . 
 p.s  i check on some schools here in town  to see if i could pick up a class on cad /cam . it is very sad  no classes, closest class is 165 miles  one way.  
  once again thank you for helping me 
 Mike