Sorry for the delay mate, been out on the islands working for a couple of days. About the only other thing I can think of is to check the plug where the flylead from the antenna plugs in - it should be about 6 inches down from the antenna itself. If that looks OK, and the cable between the antenna and the unit tests OK with an ohmeter, then my thought would be that the antenna has had a heart attack. Replacements should still be available though - any LGC-12 or 12S will do the job. I've still got two or three here in stock, so you should be able to get them in the UK. 170 quid sounds a bit rich though. If you have no luck with cabling issues, give me a shout, I'll lend you an antenna to test with, so at least you can be sure what the issue is.
Cheers mate - Chris