[Quadman]

Thank you guys for your comments and help, all very useful and appreciated. You seem to have tracked the manufacture down and the more I look at the head the more I think that a repair to the existing head is a hopeless task. However it is easily removable and a different high impedance valve type head on a suitable adapter plate is a strong possibility. Luckily I have access to a well equipped workshop and as a model engineer can do such things. I will keep a lookout for a suitable replacement at this seasons rallies.

Kind regards all

Paul