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Either the harness to the engine from the control is not properly connected, corrosion etc. or the switch itself is bad. If you look under the control you will see the trim harness. With a voltmeter or 12 volt test light you can check for voltage. Voltage on the hot wire, when the up button is pushed you should have voltage on the blue wire too. When the down button is pushed you should have voltage on the green wire. If no voltage on the green or blue but voltage to the switch then the switch is bad. If you do get voltage then check all of the connections under the control, they are bullet connectors and the same back at the engine. Repeat the voltage checks at the engine if the switch checks out fine.
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