Below are listed those faults for which 2 or more hours were lost.
The ALFOSC aperture wheel got stuck. After visual inspection it was noted that the 1"0 slit was partly out of it's slot causing the timeout of the aperture wheel. It was found that the slit mask was loose in the holder even after tightening the screws on the holder as much as possible. Several other positions were tried, but in none of them the slit mask could be fixed properly. In the end, some tape was put on the edges of the slit mask after which it could be properly fixed. The general idea is that because of continuous use (this is probably the most requested slit) the edges of the slit mask have worn thin. As a precaution, we are currently checking the masks and the aperture holders to be sure that there will not be similar problems in the future.
After pointing to a target one of the SOFIN CCD camera did not respond. The earth leakage breaker for the instrument was found to be tripped and was switched on. After this the telescope was found not to respond anymore, and subsequent reboots gave repeated "Building Power-on Failed". The next day it was found that one of the fuses for the building power supply unit was broken and it was replaced.
It was noted that the earth leakage breaker for the power to the instrument actually cuts the power to the whole adapter. This has caused the telescope to switch off and probably caused the fuse to break. This has been modified such that the power supply for the instrument is separate from the rest of the adapter, and a failure of the instrument will not cause a problem with the telescope.