I know the 175's have an AD or service bulletin about the motor mounts cracking the firewall. On another site there are pictures of a few planes firewall that the motor mount was actually broken off in a couple of places. Guess the extra weight from carrying the cowl on the 175's doesn't help. That is the first thing I looked at when the plane got here. The Prop Balancing does make me feel more comfortable considering all the problems I already had. It will be nice to have a "real" Annual!!