ANSWER
Alan Thicke. The "Facts of Life" and "Diff'rent Strokes" themes were co-written by Gloria Loring and Al Burton. The "Wheel of Fortune" theme was replaced in 1983 by a new version written by Merv Griffin, who also wrote the music for "Jeopardy!".
In addition to being an actor and composer, Alan Thicke has worked as a writer and producer, most notably for the Martin Mull and Fred Willard classic, "Fernwood 2Nite".
WHO GOT IT RIGHT: Robert Walker, Bob Milligan, Robin Campbell, Jon Dueck, Trish Boggs, Daniel Desy, Allan Christensen, David Evans, Marc Quinlivan, Yanitz Grinell, and Jim Ahumada.
