That looks like the original beckson port. It is a builder grade port that has reputation for leaking once the gasket deforms and the gasket is a bear to replace. I have replaced five of those gaskets, they took forever and the fifth one always leaks. Yes I tried hot water, soapy water, stretching and all the other tricks. You are right to consider replacement but for all the effort why not replace them with a better quality port? They are mounted in an area that has a plywood core which might have some small water intrusion so have some west system ten six ready. It is nice and thin so that it runs into any voids.
Good luck.
Here are the instructions to replace the gasket.
http://www.beckson.com/installgasket.html
I agree with njlarry on two points. #1 replacing the gaskets is a pain, but I got better at it with every port I did. #2 pictures would be great. Better yet, you may want to start a thread for the entire project. Do all of your posting with pictures only on that thread. You will then have a complete document on the entire project with discussions on hows and whys of everything you did. I did it a few years back and I enjoy going back and reading it occasionally. Joe, 25yearslater, had a great thread for his project.
Now as for replacing the ports, Think twice before replacing the ports with the same Beckson port. What will you gain? Shiny new plastic frame? That may be of value to you but you will get nearly the same result by the much simpler replacement of the lens. I do agree that you may want to remove and reinstall the ports just to clean up the old silicone and check for leaks getting into the core.This looks like a good instructional video. I followed the same procedure.
Njlarry mentioned "Ten six", this is used to seal the core so no water can leak into it. Builders often skip this step and wet cores are the result. The epoxy must be completely cured and trimmed up before you reinstall the ports. Silicone is used to seal the ports so you can remove the port at a later day.
Here is the info needed to identify parts for the Beckson ports. Yes, I too buy from D&R whenever possible but this info is important to have on hand.
https://www.beckson.com/component.html. The proceeding was just my two cents. and often worth that much.