Don't disappear just yet G7Michael, it is sounding increasingly likely that your problem is due to a 'stock fault' with the reference oscillator trimmer capacitor, if so, all you are likely to need is a replacement trimmer capacitor and the loan of a frequency meter or the use of some other frequency standard such as an off-air signal with a known accurate frequency.
Looks like the Scarborough lot are also still on the go:-
https://www.g4bp.org/default.php
When I suggested Hornsea I had made a quick crow flies measurement from Driffield Centre to Hornsea centre - the crow files distance to Scarborough centre is actually a few miles further so that's why I went for Hornsea originally, sorry.