Yeee.
Well done to both, you and sigma.

Glad this story has a happy ending, Ant

Nice..... beating one's expectation always puts a smile on one's face.

I recently had a look at my Sigma 70-300mm zoom, which had jammed,
very like another I had (which I had thrown away in disgust). This one
however (for the Nikon F2) I was determined that one day it could be
fixed ... Today, I unscrewed the macro switch assembly, and there was a
resounding click, and all of a sudden the whole mechanism freed up.