You are tenacious Colin, gotta give you that
...well, I recon this looks great now and as you say only the residual rings around the stars are a little annoying. It looks like gas so I certainly wouldn't
sharpen it any more at all, perhaps a little more contrast
..but even that isn't really that necessary to me as I recon a slight softness enhances this neb.
Ok... let's see version 16
Mike