I just fixed one of these exact same models with the exact same problem Friday.
Problem was caused by loose solder connections on convergence IC's (STK392-110)
causing one of them them to overload and short; also cooked three output
resistors (1.5 ohm, 2.2 ohm, and 3.3 ohm 1 watt. Customer said TV had lost
convergence "several times" before going completely.