The ball hanging up is not a level 10 issue with it not resetting if the gun will dry fire. If the bolt resets such that the gun will fire, then the bolt is working without issue and you have another problem occurring. I would go back to the smaller carrier size to stop the leaking. If the gun dry fires and doesn't have bolt stick or a leak, then you have the proper size carrier installed.
When bolt stick occurs it prevents the sear from resetting and allowing the trigger to come forward. The gun will not fire in this condition.
Check the condition of the balls. Are they misshaped or enlarged? If you have to push the balls into the breach, then that is more likely the problem.
HolySokz: If you had to install shims to get the bolt to reset, then you most likely still have a minor bolt stick issue that will crop up at some point in time. Shims don't stop bolt stick issues, but do control how far the bolt needs to move to vent air if the bolt doesn't fire or release air but can't reset.
Except for the Automag in front, its usually the man behind the equipment that counts.