[sparkymike]

Thanks Dave for the above. At first I thought it might be just a case of corroded wander plug sockets, but on removing the back cover, all the high bobbins seem to read ok, so will check out the low one next.(The day ended too quickly yesterday) As you say, it is probably quite a game to remove any of the coils, so will no doubt adopt your method. I see the later Minors had a rotary switch in line with their big brothers.
As it was my father's meter, it has sentimental value, so should be fixed. By the way, he was also local to Colchester area and was an Inspector at Astralux.
For some time he was involved in switchboard plugs for BT and I still have some cut-away ones that were made during development. From memory a complicated four contact plug.
Mike.