I've had a creak since I first started using my Atlas cranks and haven't been able to figure it out. So far, I've tightened pretty much everything under the sun but recently noticed that there is play in the main fastening bolt (the one that goes in the center of the drive side crank, holding it to the BB). When I remove the bolt, I can feel play betwen the 8mm part that screws into the BB spindle and the outer 10mm self extracting part. Did I just find my creak and I should replace it, or is that kind of play normal for a self extracting bolt?

If it's normal, any suggestions on where to look for a creak when my left hand crank is in the 6 o' clock position under heavy torque?