All, Last night I was imaging and when switching from Luminence to Red filters I got the dreaded filter wheel error.... Upon investigation, I found that the red o-ring on the edge of the filter wheel had come off of the track and was dangling inside the CFW-9. Certainly, that stopped my imaging run, as to fix the problem you have to remove the carousel to put the o-ring back in place properly. Once the carousel was out and the o-ring was retrieved, I noticed that there was a worn spot on the o-ring where the shaft of the motor had etched into the rubber material of the o-ring. I rotated the o-ring so that the worn spot was not facing outward, reinstalled and got he unit up and running without a hitch. Needless to say, this is going to happen again, and next time the situation may not be rectifiable with the original o-ring. Is there a spec for the o-ring, i.e. width (thickness), OD, ID and material so that I can order a replacement from McMaster-Carr or other reputable vendor? This should not be a "you must return the CFW-9 for an official SBIG repair" item. Doug Azwell