Hi Guys,
first of all, thanks John and David for your thoughts.
Another thing I've thought of is to mention that the LB normally rests with the tube upright. So if it stays like this for some time, then I suppose it's possible that dew forms, and because of the bowl shape of the mirror, there's nowhere for the water to run off. So I suppose it must just evaporated leaving any residue in it's wake to do it's corrosive thing.
Could this be a possibility guys? I had the scope out this evening and although the cell does look very poorly, the views appear to have been in no way compromised. I'm now resting the scope in the horizontal position just in case
