Turn off the propane and the electric, (unplug trailer). Run enough water through a Hot faucet that it runs cold. (you don't want hot water coming out and burning you when you remove the element). Now turn off the water supply, and bleed any pressure off. Also shut the propane off at the bottles. Open the outside cover, and remove the burner tube. 1 screw and where it connects to gas valve. Behind the tube is a round/black plastic cover held in with three screws. Remove the cover, and this will expose the electric element. Remove the two wires from the electric element, don't worry about color or location, doesn't matter, as these are AC power wires. Now with a special water heater element socket, unscrew the element, (turn to the left). When the element is almost out, stand back, as water will drain from water heater.
Elements and special wrench available at big box hardware stores. Wrench is not much, and elements are $12.00 or so. Good Luck, and make sure that the water heater is full of water before turning on electric. Don't check inside, open the "pop-off" valve outside and make sure you get water, and a steady stream.
Many folks have bleed the lines inside thinking their water heater was full, when in reality, it was in winter by-pass mode and completely empty. Thus when they applied power to the electric element, it immediately burned in two.
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