Chevrolet Repair: 2000 silverado, thrust bearing, distributor shaft

Question
the gear on my distributor that is turned by the cam shaft keeps getting ground off I have replaced it 5 times every 1300 miles it is ground off again. I started with the easy stuff I replaced the distibutor and the oilpump, but it is still doing it. I am currently in the process of removing the camshaft. Is it possible that the camshaft is bent? what could be causing this  

Answer
Hi Frank,

I wonder if the thrust bearing or plate that keeps the cam in place, is worn.  If so, the cam could float forward and backward causing the teeth to not mesh and come apart.  

I would think a bent CAM would cause binding up, but possibly that could be it.  Try pulling out the distributor, and have someone turn the key, as you look down the distributor shaft hole.  Is the CAM wobbling?  

C J S