Sorry you still have that problem, Sheila. The "a" thing is the anode rod, but other than that I haven't a clue how to even remove it or even if I have one! I just remember my DH hunting for RV repair places on one of our trips to replace it. Usually, I think, the water smells a bit like rotten eggs? Do you still have the owner's manual papers? Maybe you can find a drawing in there that your son can use.
I know we had to replace the faucet one time when that on again, off again water happened to us but if I remember correctly you have having the same problem with all your faucets - right? Ours was just the kitchen.
I don't use my water heater very often mainly because my shower is so tiny that I use the RV park's facilities. I have a little electric hot pot for most hot water uses like dishes, etc. Who am I kidding - I use paper plates!
How are you managing in the driveway? Everything going okay?