Billybob, thanks for the lead, that looks very promising!

Being a relative noob to this type of work (but a fast learner, I hope), I have a followon question or two.

Yes the original bolt is 10mm-1. I verified this at two stores with their sizing templates.

The nut at this time is partly stripped out. Parts of coil (helicoil? I don't know) fell out during the initial extraction - looked like part of a coiled spring so this was clearly an insert of some kind.

I see the KD Tools "uses the good threads at the base of the port" per the description. I can't be sure there ARE any good threads, I can say there is some stuff left over inside. Is it possible it would work?

Also, given the original threads are probably an insert, isn't the original sleeve (prior to any insert) slightly larger than 10mm, as the insert would take up some size on its own?

Feel free to PM. I appreciate your posting this and hoping I can find a way out of this mess. I did use propoxy 20 per a prior recommendation and it ALMOST did the job, but a small leak has made itself evident. I may even re-patch it with the same material to create a 'dam' effect.

Edit: Looks like you forgot to paste the link for that other tool...