Hi Greg,?
Pretty easy.? If it is tight, winding the worm by hand, it's probably too close.? If you can significantly move the axis by hand, with the clutch tight, then it's probably too loose.?
I've done a lot of imaging with both Gm8's and G11's and found that having the worm ever so slightly loose is far better than trying to eliminate all the play from the axis.? This is true for both RA and Dec.
My 2 cents worth...
Eric
Eric Chesak