Secondary top unit

It is clear that the secondary displacement unit has not been working properly at least since the aluminisation of the telescope mirrors in June 2014. Various adjustments and tests were made, but none of which has explained or fixed the problems.

The whole displacement motor/gearbox/linear mechanism was replaced with a spare. After installing the spare, the same variations in the position remained, so the original motor assembly was put back. In addition, the metal plate the displacement pin pushes against was moved such that it now presses again a flat smooth surface, though this has made no change to the performance of the displacement mechanism.

Further work is being planned.