[Mart]

I've never taken one out, but are you sure it's threaded? Not just grooved? Hard to see in the pics. I think you have to knock or press it in. It would be worthwhile asking the machine shop how they removed it. I have seen the subject discussed before either here or on the hamb so more info might be out there. I seem to remember someone saying to remove it you tap one end and pull it out. It might be worth looking to see if one end has been tapped.
I will be interested to read any other comments.
Mart.