My M. M. starter, PN 541-530, failed because the drive retaining nut (PN 149-900) became detached from the drive shaft. I suppose this happened because the cotter pin was not put in place and I missed it when I installed the new starter. When the failure occurred a 2" hole was blasted through the cast iron clutch housing and I found the nut on my garage floor under the car. The main spring (PN149-900) is now jammed between the flywheel and the clutch housing and the engine is jammed. Looks like I may have to tear things apart to get to that spring. I am planning to either braze or epoxy a metal patch over the hole in the casting. Does that sound like a good idea? The spring is barely visible with a mirror and I don't see how it can be removed in place. The starter is under warranty but the rest will be on me.