Thanks for the replies. Perhaps I had an earlier version of the adapter, because mine did not have holes in it. I have now tried a jar opener, and in desperation have drilled and tapped to screw holes in the adapter and tried to use a metal rod as a lever to unscrew the adapter. Unfortunately the bugger is stuck fast. My last effort might be to remove the CCD chamber housing (the black round part) and heat up the casing to a higher degree and ice the adapter and try that again. Sheesh, I had no idea this would be so hard!