You have the 'older' version of water heater--Atwood redesigned their WHs in 2004
GCH10A-3E (Gas Combo Heat exchanger 10 gal 3rd version Electronic ignition)
Your version has separate set of t-stats for each heat source
Your version has direct AC power to electric element---no circuit board control for electric
The element and t-stats are mounted on backside of WH Tank
120V AC power from Circuit Breaker to On/Off switch to the set of t-stats then to element (Black wire 120V Hot, White wire Neutral, Green wire GROUND)
On Edit:
Had to take off this AM before finishing info.
Check the ECO (Hi temp t-stat) ----may need 'reset' (manual button on ECO)
Also should be an OEM On/Off switch locally on the junction box cover over element and set of t-stats
