I have a 10 year old A.O. Smith 66 Gal 1400 Watt dual element electric hot water heater. Water out of the fawcet starts off hot but gets cooler as time passes. I first thought the lower element was bad but I'm not sure. I checked the thermostat settings on both elements. Top is set for 130 and lower is set for 140. I can listen and hear water boiling around each element. I measured the voltage across the element terminals and the top measures 240 VAC but the lower only measures 74 VAC. I was going to check continuity across both elements but figured since I can hear water boiling both should be ok. Any ideas? Thanks!