I had a go at tackling the leak from the cistern feed last night. PFTE tape didn't seem to do the trick, in the end it looks simply like the plastic screw thread wasn't flat enough to mate cleanly with washer. After dinner and Newsnight I thought I'd try fitting the old inlet valve mechanism. Unfortunately I gave it one turn too many and it snapped off. It's times like this I'm glad I fitted those isolator valves.