I've requested a quote from a Qld O-ring supplier who seems to have what I want. No reply yet - I guess it might be because I'm not ordering hundreds!
No running around - it's got to be solved from my keyboard!
I don't like using my time and petrol any more.
BTW, Boojan, O-ring for a finderscope is good enough IMHO. For a guide scope etc., nope, I expect not. In fact I love the GSO mount - one spring loaded pin and two screws at 90 deg - so intuitive and quick to align. I wish my good finderscope would fit in the mount - sadly it doesn't and I have to use a three grub screw, three knurled knob adjustment screw mount. It annoys me.