Hi , you maybe going in the right direction but. you need to know this fact. you are working with a directional contact. This means power flow via normally open and the normally close other side. This unit may also have a by direction Pot. and you could have a bad side to it. As for $800.00 for the contactor, you may want to look at going elseware for parts. that more then twice what you can get that for.
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