Another great video by Patty Butcher, demonstrating how to adjust the iQ motors. Pay attention to how much to loosen and then tighten - as Patty says, only teeny tiny turns. Never, ever loosen them a lot - it will be so much harder to get the correct adjustment.
NOTE: Patty is working on an APQS machine. On my Gammill I couldn't use the carpenter's square as Patty does to check that her motor is straight - I had to hold a straight edge and compare it to a straight edge on my track. I've shown that in another post.