Cracked section in my "new" esterbrook series J

Worst part is I may have done it. I tried to disassemble to make sure everything inside was good but I couldn't get the section loose. I tried heating (used the lip test to judge temp) but the section would not budge. I decided to stop but I must have cracked it by then.

Part of me wants to think it was glued in rather than shellaced but I have no way to know.

I have had esterbrooks before and never had a section not want to come out. Nor have i had a looseness problem that called for shellac or glue. Either way one should not manhandled a nearly 70 year old pen.

I'm not too proud to just patch this but what would work good to prevent the leak and prevent the crack growing under gentle use?

I was thinking a quick swipe of superglue on the outside so it didn't go through the crack and block the nib threads. Alternately I thought of some melted wax which would be more "undoable" should I need to back out.