Depending on what tools you carry and previous experience, seized screws extraction can be relatively easy without harming the fin clamp.If a screw is seized, try not to force it out. It will either brake or the Allen head will be destroyed. Then it becomes a an issue.
So I f you have a seized screw or more than one, or all of them… remove the fin clamp, put in on a Vice and use a blow torch to heat up the metal. Be patient, at some point the screw will turn and without a lot of force. I’m this case if you clean all the residues and put everything back together, it will be good as new.
If you have already broke or damaged the head… then you are going to need a very good and precise bench press and a good cobalt drill bit, (I use a M4 drill bit). And a precision Vice.
I usually drill off the screw without harming the threads. And only need to run a 10-32 tap to clean the threads, and put a new screw in.
if the threads are gone, you can always use a Helicoil insert or timesert… you don’t need to size up. Also helicoil and time serts are good for repairing striped threads on some not that durable clamps.
anyway, I wouldn’t throw away a good fin box because of a seized screw, but I wish when friends are bringing me one to fix that they wouldn’t have tried to apply to much force to the point the screw is damaged or broken..
I’m the picture is a removed screw that came out without harming the aluminum’s treads