Autotronic's post 13/11/2010 was correct about the control panel selector knob.

I took it apart this afternoon and the small dome switch was misaligned. however i found it impossible to re align. There are a couple of components within the unit that have to be realigned, but that can only be done with some disconnecting of 2 soldered tags and then resoldering after the alignment.Then you've got to put the switch back together again keeping all components aligned.I didn't manage it, so would not recommend the procedure.

I now have to find a replacement Unit before i can sell it on Ebay or use the whole panel for future spares.