I bought the AZ-EQ5 a while back and it went ok on the first imaging run but with a few jumps, so I adjusted the worm gears today according to this guide:
http://www.astronomo.org/foro/index.php?topic=17215.120
The gear mesh was a little loose on both axes but the bigger issue was that the Dec axis worm end float needed adjusting too - the worm could be seen moving back and forth longitudinally.
Hopefully the next guided imaging run will be as good as my AZ-EQ6.