To replace the TPV on a water heater a plumber will have to buy a new one. After switching off power from the mains and closing the main tap, the plumber can then replace the new TPV .
YOU DONT repair them
replace the water heater inlet pipe on the intake manifold on a 3800
ring a plumber up
What you have to do, is replace the heater core itself
No way to fix that - your tank is scrap.
Human nature being what it is, wait until the first sign of water that shows up in the catch pan that the heater sits on. This is definitely time to replace the tank.
Regular insurance will not. If you just purchased the house and have warranty insurance and the water heater is listed it will.
If your modular home has a regular gas supply that is a satisfactory way to do it.
you need to replace your heater core.
Remove the water from the cooling system. Remove the water hose from the heater core. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
Follow the attached link -
There are many pictures of this on Google.