I have a Dewalt DW131 1/2" drive drill. I am having a serios problem with the set screw that holds the chuck to the drill. When using the drill in reverse, the slightest bit of pressure breaks the set screw. I have broken 5 in the last week and a half. Has anyone had this problem? It is supposed to be an extremely heavy duty drill and I am wondering if it is maybe a safety feature to keep the user from getting injured or if it is just a poor design.