Ok further info..
It actually doesn't find a tune... I'm not sure if something has changed or if I just didn't notice earlier and presumed that it had tuned... but now it shows 5W on the display when tuning into a resonant antenna.. I hear the usually whirring and clicking from the tuner... when that stops it does display the "--"
I was a little reluctant to start really pulling the radio apart as it isn't mine... I'll have to confer with the club radio officer before proceeding but will pass on your suggested next step.
Thanks... I'll post as we move forward..
Richard // N2GBR