What if the Senate Can't Convict a President?

Ruben Navarrette: The Senate fell 10 votes short with a 57 to 43 guilty vote, including an unprecedented seven Republican members who voted to convict the president of their own party. He says Section three of the 14th amendment provides that any person who has engaged in insurrection or rebellion against the United States cannot hold office. But it's too late now to make it up on the fly, he says; we have no idea how to use it.Navarrette: If Congress passed a new law purporting to change the age of eligibility from 35 to 40, would that be constitutional?