Below are listed those faults for which 2 or more hours were lost.
There were continuous problems with filter wheel no. 2 not reaching its position when moving it to a specific position or when initializing it, which resulted in large amounts of time lost on two nights. As it takes at least 10 days to warm-up and cool-down the instrument this could not be investigated in depth during the observing run and it was decided to change the instrument to ALFOSC.
This was very unfortunate as a lot of effort was spend at the end of 2003 with a complete overhaul of the bearings using new standard commercial bearings. In the end we decided to return to the original method we used with bearings that have a limited lifetime.
The filter wheel no. 2 now failed intermittently throughout the observing period with NOTCam, but it was still possible to reach the desired filter positions after several (many) tries.
After warming-up the instrument it was found that the bearing for the wheel had not been properly installed after the last problems with the wheel. The bearing was replaced.
It should be noted that for both these problems the amount of down-time does not take in to account any reduction in science return from the observations due to the limited capabilities of the instrument.