Arca Swiss Monoball Servicing - UK

Does anyone know of a reputable organisation in the UK that will undertake servicing of an Arca Swiss Monoball?

Mine is basically the same as this one, the Z1sp, but an earlier model. It has the 3/8"-threaded circular plate, not the quick-release top.

Mine had seized up; I've freed it, but it could do with some care and attention from someone equipped to reset it properly.

I suggest you contact a retailer who sells Arca Swiss equipment and ask them who the the importers are, they should have a service facility.