I decided to replace all the easy components of the water heater, which included the anode rod, the upper and lower thermostats, and the upper and lower elements. I started by turning off the circuit breaker, and using a non-contact electric tester first on a live circuit to confirm that the tester was working, then applied it to the wire into the water heater to confirm that the power was cut to the water heater.
Replacing the anode rod required me to buy a 1 1/16" Craftsman chrome 12-point socket (though I would have preferred 6-point if I could find single sockets) as the impact socket from the set I had did not fit into the recessed hole for the anode bolt head. Using calipers I measured 1.45" and the impact socket diameter was 1.48". I started by draining some but not all of the water to keep weight in the tank to help keep the tank in place due to the torque required to break the anode rod thread seal. I opened all of the hot water faucet to let air into the system to assist draining. Using a 24" breaker bar with a 1 1/16" chrome socket, I was able to loosen the anode rod and remove it. The force to break the seal was not what I would consider excessively difficult.
The next step was to clean out the residue from the old seal. I took some CLR soaked paper towel with some small pipe cleaner using up and down motions to try to remove the old pipe dope. Once that was done, I decided to get some water from the sink (that had the hot water faucet open) and I noticed that the flow was not quite right. I ended up going back to the water heater and noticed that I had water coming up out of the anode rod hole (enough to spill over, but not excessive). I realized that running the cold water with an open hot water faucet valve had backflowed cold water down the hot water pipe into the water heater, oops! So if you need cold water from a faucet, turn off the hot water valve first!
After some cleanup, I was ready to install the new anode rod. I used 4 wraps of MEGATAPE brand of PTFE tape for the anode threads (ratings said not to use it over 1 1/2" pipe, with pressure exceeding 300 PSI, and to use 4 wraps). It took considerable force to slowly tighten the anode rod with the 24" breaker bar. I eventually stopped when turning the anode rod caused the water heater itself to move. I had another person help keep the water heater from moving during this step so that when I got to the end, it was obvious that the anode rod was torqued all the way.
I decided to test the water seal first before attempting to replace the heating elements. I restored inlet water pressure and pushed air out of the system. Once water was flowing through all open hot water faucets, I closed them all and waited 10 minutes for a leak. After 10 minutes, no water was discovered in the recessed anode rod hole and I felt confident that the seal was solid.
At this point, I decided to replace the upper and lower heating elements. I opened the water heater tank drain valve and then shut off the inlet supply (helps to purge any sediment that may be there). I used a red hose that supposedly is more safe for draining hot water. After some time, I decided to start replacing the upper and lower thermostats.
To access the upper and lower thermostats, I had to remove two panels and then lift insulation and remove the plastic protector panel. I used blue tape to keep the insulation out of the way. At this point I took a couple of pictures to make sure I put the wires back in the correct terminals. The upper thermostat had six screw terminals and the lower thermostat had two screw terminals that I loosened to pull out the wires. The most awkward part of replacing the thermostats was to rotate to two clamps on the left and right towards me and simultaneously push the thermostat body up, which took me a while to figure out. After you figure it out though it's straightforward to put the replacement thermostat in. I was able to reconnect all the wires.
At this time, I noticed that the water slowed down and when I opened the cold water inlet I got an audible echo from inside the tank from water hitting the bottom. I then removed the wires from the upper and lower heating elements and then the element itself with a 1 1/2" impact socket and the 24" breaker bar. Seating the new heating elements was a little awkward as they are a little heavy and tend to want to tilt down, but persistence got it done. I reattached the wires, then put the protective plastic shield back on, then folded the insulation back over and restored the panels.
I closed the water heater tank drain valve and started filling the water heater tank and after a few minutes saw water coming from all the hot water faucets. I then closed all the faucets and turned the circuit breaker back on, using the non-contact voltage tester to confirm power was on. I waited a couple hours and measured the water temperature and I had hot water.
So far it's been two weeks and the hot water has been solid. Material cost was about $110 from supply house, plus the extra socket and red water hose. I'll see how long this lasts, but hopefully it will give the water heater a few more years. The difficulty was not hard, though having another person to help with the anode rod was pretty nice to have. You can see a picture of the old heater components.