Yes I have the user manual, and the service manual, but it has no reference on how to release the locking mechanism. It explains how to completley dissassemble it.
Those pics showing how to remove the film would normally work for me, but my negatives have gone deeper inside the scanner. There is another reference to fixing this problem, but it does not help me find the lock release:::::
if you take the cover off, on the left hand side of the scanner (with the front facing you) there is a little opening cut into the metal box which holds the adapter. There's a little metal tab which engages only when there's film in the adapter. this stops the adapter being removed. Luckily it's spring loaded, so you can push it in and slide out the adapter as normal.
But the above text has not helped me find the metal tab. Its still stuck in the scanner.