Maybe a Clear Adapter should be put as it's own post as I thought this was just about mandatory to know when the tank it fully flushed.
If your lugs are worn down, you should be able to cut off the older model, leaving enough of the original PVC left for a new model to be glued onto. If this is German to you as it was the first time I looked into lenghting my cleanout connections, go to your local RV Dealer and they should be able to walk you through it, or do it for you for that lovely price of $90 per labor hour!
Good luck and I'd do this first thing, as Dry Camping isnt to fun when you have to look at that bathroom in the middle of the night but cant use it.