We have seen a few tilt locks break on the MAC III and after some investigation found out that it is mainly because the tilt lock has been applied while the fixture was being shipped in the flightcase. The foam insert in the MAC III flightcase is designed to absorb shocks and is perfectly capable of protecting the head and yoke during transport and handling. The tilt lock is not designed to withstand the sometimes severe shocks that time-pressed roadies or freight handlers can subject our fixtures to, so:
MAKE SURE THAT THE TILT LOCK IS RELEASED EVERY TIME YOU PUT A MAC III IN ITS FLIGHTCASE!
We have initiated several counter-measures to help this issue (like a stronger tilt lock and warning stickers which will be placed on the inside of the flightcase) but none of these steps can guarantee that the tilt lock will survive rough treatment of the flightcase if the fixture is packed in a flightcase with the tilt lock applied.