I forgot about this topic.
I centered both the main shaft and the idler shaft and tightened the allen screws. I have not had any problems with this drive since.
This drive was initially hardly used because I have three drives between the AI and TI. I suspect the allen screws were not initially locked down as tight. I have added a allen tool to my repair kit and check this part more closely when doing maintenance. I do worry about stripping or splitting the plastic piece.
2011 Adventure Island (Little Dog)
2010 Tandem Island (Big Dog: "We keep a leg up on the competition")http://dogslifeadventures.blogspot.com/