The seized azimuth gearbox on ak01 was recently swapped for a working unit from one of the other antennas (ak34) that does not currently have a PAF installed. This process provided an opportunity for the MRO site mechanical engineering staff to gain direct experience with the gearbox mechanisms, a first since they were installed by the manufacturer several years ago. The failed unit will be sent for inspection and rework while CASS is in the process of sourcing spare parts for the future. In response to the need for more regular monitoring of drive train health, we have developed a standardised torque test program that drives all operational antennas through a predetermined sequence. Subsequent analysis of the electrical current required to drive each of the motors during this test can provide early warning of excessive binding in the drive train. As a result of these tests, some adjustments on the meshing of other gearboxes has been performed, but overall the remaining antennas seem to be in a good state.