Mike, I had exactly the same on my both DEC and RA and fixed it yesterday using this page as a guide
http://timsastroblog.blogspot.com/20...p-for-eq6.html
Or in your case with play in DEC I guess
this image explains what you need to do.
It's worked for me and there is no play left at all. Just remember to test it right after you adjusted these small screws. I've found that if you tight them a bit harder than required there will be this weird sound when the head rotates.
To test it turn your mount on, set it to the highest speed and using all four directions buttons on your EQ6 had control try to rotate at least 90 degrees from your home position.
hope it'll help because I know how it can be annoying when play is noticeable.
P.S. If it's just a top dovetail head play then there are thee top screws located in holes that need to be tightened.