Karen, I had the same problem with my Trillium
4500, the covers break off. Solution was to replace the assembly by drilling out the rivets, extracting the old fitting, and installing new fitting. I liberally applied butyl tape (from camping world, etc) behind each new fitting, then re-attached with stainless steel screws (could use rivets).
Here is an Amazon link to replacement RV "cable hatch" :
Edit: Some people get rid of the cord port, and replace it with a power inlet, then use a separate cord.