Morning Bryan. Contact Dave at Leeches Gunsmiths in Boreham -- approx eight miles from Witham. He/they have been quality gunsmiths -- including air guns -- sine the 1960s. They used to have a shop around the back of Chelmsford High Street until the early 1980s, too, but economics and changing social attitudes saw them consolidate at their workshop in Boreham.
They/Dave has worked on several of my air guns and rim fires over the years (including the feed on my old BSA Goldstar multi-shot springer which no one else was willing to touch), and the HW80K he brought back from the dead for me after another 'alleged' air gun specialist had butchered it, ended up being one of the nicest HWs to shoot I have ever owned and on an equal par with my SFS HW95K
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Hope this helps. Atb: G.
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