I had the same problem as you Pepin. So I replaced the bottom gudgeon with an ordinary pintle making sure it was the same make so the fixing holes lined up. Then I cut the long bent pintle just below the top gudgeon. For some reason the pre drilled hole for the retaining "O" ring was placed just below the top gudgeon so there was no need to drill another hole. However, with the right sized bit and plenty of lubricant and patience drilling a new hole is possible.
After this refurb I don't remember having any further problems removing the the rudder cassettes on Stealth 516