Pearson 424 tang bolt

[Brion Toss]

Hello,
You are reaping the results of a truly awful mode of fabrication, a "compression tube" of aluminum, on a stainless bolt. Over time, galvanic action welds the two together. To make matters, worse, there's only a nut on one end, and they only made the hole in the mast big enough to take the tube out at the nut end. So yes, you will need to cut the head of the bolt off to get the thing out.
When replacing, I recommend that you use oversized collared bushings in the mast wall, to recruit more aluminum molecules. This should allow you to use a smaller diameter bolt, too. Put a nut on both ends of the bolt, and have the threads cut on a lathe, such that the nuts can only just barely snug the tangs down against the mast; no compression tube needed, less weight aloft, and you can remove either tang if needed.
Fair leads,
Brion Toss