The next surprise was when the fin refused to separate and bent the presses securing pins:
It turns out that I had the angle iron too far outboard. The levelling plates got the fin in place but kept the iron too far away from the centerline. Breaking out the oxy-acetylene torch I reconfigured the angle iron to get closer to the center.
So at the end of a full day's work I have one booster's fins added to the refinishing pile:
Til next time....... Blazing Skies!!