Ninety-year-old Jim Jones is sent back into his 15-year-old body in 1964 to help Betty Knox (who is already back in her 15-year-old body and doesn’t expect him) because all the time-travel agents (sent back to that time to avert the world’s toxin disasters) have disappeared with no discernable effect on history.
And I know that after Johnson, Richard Nixon is elected president. Then comes Ford. Who comes next?

Variants

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  1. “Betty Knox and Dictionary Jones in the Mystery of the Missing Teenage Anachronisms” by John G. Hemry, in Analog, March 2011.
  2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . written by John G. Hemry