These are Gebo hatches, which is easy to tell because you can see in your own photo that they have "Gebo" written on the aluminium frame
While it's good to have a set of spare handles aboard, usually if they're leaking you only need to replace the O-ring under the outer part, which eventually perishes from UV exposure. You can take the handles apart from the inside by poking a pin into the small hole in the handle, depressing the blue latch retainer so the latch slides out all the way, revealing the screw that joins inner and outer part.
Gebo hatches are original to boats of that age and you're lucky to have them.
