Washington radio station WGMS dropped the music of Mozart and Tchaikovsky yesterday after nearly six decades and replaced its classical format with tunes by Cheap Trick, Elton John and the Bee Gees in a two-part shake-up. Last night, WETA dropped its news and talk programming and became a classical station again in a coordinated move with Bonneville International Corp., which owns WGMS (103.9 and 104.1 FM). WETA (90.9 FM) was a classical station for 35 years until dropping the format in February 2005. snip But Bonneville is entering a highly competitive segment of the radio market. Its new station replacing...