I have just been experiencing this same problem with my Atwood water heater.
I was able to find a replacement by getting the model number off the unit, then calling around to Camping World and RV repair places.
I was afraid to try to determine and order this myself, but the parts people are really good at this.
I found a parts person who tracked the exact part down for me, ordered it from one of their suppliers and will ship it to my home.
🏡 🚐 Cherish and appreciate those you love. This moment could be your last.🌹🐚