If it's an issue with the pin, I'd first make sure there are no hairline cracks around the pin on any of the mating parts.

Once you have confirmed that, you could try removing the pin and then coating it with nail polish or something stronger. I expect a small coat would be enough, otherwise multiple thin coats will be stronger than one thick coat.

You are going to be pushing it to coat the inside of the pin hole in any effective way that allows you to reinsert the pin.

If there are cracks in the plastic, you can try to remove the pin and glue the plastic but on something so small it's going to be tricky. you'll want a glue that's very strong but something that isn't going to discolour the surrounding plastic. also a very small application as you don't want to fill or partially fill the pin hole.

best of luck.