Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
But of course he's going to be buying the whole assembly from you Ash so he doesn't need to remove them
My 500 did not have a screwed in retainer pin Ash I had to drill it out. The bearing at that end was partly missing as it had been dismantled previously. I ended up with a replacement mounting unit from Ken that had a been later threaded and fitted with a one piece threaded pin.So if I understand you correctly it's a two part arrangement on the 500 threaded with an end cap fitted on assembly to hold it at the right position!