Why do the blades disengage in the middle of mowing

I changed the clutch and the problem continues, the blades disengage in the middle of mowing. They come back on but dont stay on. What can I do ?

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check to make sure the belt isn't slipping

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Is not the belt. Or the clutch. I checked those. Seems to be an electricla problem, because the belt is tight the tension spring is new and so is the clutch.

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