1994 Cadillac Seville Starter damage

Replaced what seems to be an orignial starter on 1994 SLS Northstar, once removed from engine the starter bendix half dome cover was craked in two. Inspection of driveplate revealed on damage to teeth and all driveplate bolts secure. Replace with a rebult starter and after about 5 starts the same problem, dome cover cracked in two with no damage to driveplate. I am not sure if a another starter is going to fix my problem and it doesnt appear to be the driveplate. We brought this car for my son last July 2007 and have had no starter problems until now. It I had some real damage to look at I could tell which direction to go in - another strater or driveplate.
By the way all damaged parts from each starter were recovered, has both cracked clean in two.