Thanks John, I'd found that link but my problem is my Betax #3 looks quite a bit different internally, it's also missing screws and those US thread screws are non existant in the UK
However I also have a Betax #4 that has two broken aperture blades and a missing spring, I may have a replacement for this soon and that will then be a donor for screws etc.
The last two Camera fairs I attended I bought 7 good working shutters, 6 at the 1st and one I'd missed (same seller & box) at the 2nd but there was an Alphax which wouldn't cock and it was probably a #3, it might help me out - I have the stall-holders card & contact details and he's less than 15 miles from me
I gues I could post some images of the shutter as it is and maybe someone will spot what's missing . . . . . .
Ian