When actor Lionel Jeffries turned to directing in the 1970s, he exhibited a preference for whimsy, as witness THE RAILWAY CHILDREN. Jeffries' BAXTER is a notable exception to this rule, though, as with his other directorial efforts, he shows a keen sensitivity for the travails of troubled youngsters. Scott Jacoby plays Baxter, a boy with a marked speech impediment. His affliction worsens as his parents' marriage disintegrates. Patricia Neal plays a dedicated speech therapist who realizes that Baxter's problems go deeper than his inability to speak normally. BAXTER was scripted by "Golden Age" TV veteran Reginald Rose.