Does this error move with the player? I.e. attached to another TV, does it show the same lines?
If yes, I would assume a PSU "weakness", probably smoothing cap.
However: as this is a switching PSU, high voltage is present, so poking around is lethal, unless you know what you are doing.
Elektrotanya has the service manual including full PSU schematics (and measurement instructions throughout the whole unit, with waveforms). Maybe check the output signals according to service manual first, you will need a scope.