I have completed a manual controller for the shutters on the large dome, and installed it on Saturday 14th July 2018. It completely replaces the automatic controller which is faulty. Final adjustments made today mean that:
1. Both shutters stop automatically when they reach the limit of their travel.
2. I have removed the interlock which prevented the lower shutter opening or closing if the upper shutter is closed. It is now the operator's responsibility to implement Upper Shutter Open First, Close Last.
3. The lower shutter now closes properly.