Lately an ST-i shows erratic behavior: sometimes it works fine sometimes it gives dark images only. CCDOps is used with the latest drivers. Closer inspection of camera showed that a small round magnet is attached to the shutter and was only held by the - weak - magnetic force of the magnet. It could shift on the shutter easily or become detached. See image: magnet inside the coil. Is this normal? Could this be the cause of the problem ?