Is this addressed to me? ^
Happy to help but DavMen is in the next state and could be a thousand km away so it won't be hands-on today.

OK. Here goes with web help.:
The base bolt is screwed into the Bodge joint female thread, probably with Loctite. I have found that old ones are sometimes very reluctant to part company.
Put the rubber joint in a vice (or Stilson pipe wrench) and get a socket spanner (6mm?) onto the bolt to remove.
If successful: buy new PJ with female thread and but the bolt in the new one with some Loctite. Do not overtighten with large lever to it may fracture and will break on your first sail (or soon thereafter)!
If unsuccessful, grind or cut away all the rubber to remove the metal part containing the thread from the PJ. It actually has a hex bolt head on it which you can attach a spanner to to hold it better and use socket spanner to get it undone. (I actually did this last week)
If that is unsuccessful, (you break something?), go to the shop and buy a new base insert part to screw into that new PJ you bought in anticipation of it coming undone.