About a month ago is when my engine pooped out and after tearing down the engine I found that the electrode on one spark plug had broke off and pretty much destroyed the cylinder and the plug is pretty much smashed/stuck in the housing. Have any you experienced veterans ever heard, seen, repaired an engine where the electrode broke and caused significant damage? My buddy has seen three incidents of it, all bmws (though different engines), and all used Bosch plugs...