I am getting back into using my ST-402. However, an old problem (present since I first purchased the camera) has reappeared.
I thought I had it fixed, by tweaking thetightness of the washer on the centre wheel.
The (internal) filter wheel is out by 45deg (in a clockwise direction) on each filter, blocking the CCD chip from any light.
Might someone have a suggestion, before I go to the trouble and expense of returning the camera to SBIG.