I have a sansui g-5700 stereo receiver with a tuner display problem.It has the the G-3000 board.The display itself has a black burn spot in the left corner.Anyway to replace the actual display and or the board?The quartz lock does not work and the numbers are froze and missing a couple of segments.Signal strength indicators still work.Main concern is what caused the black burn spot in the upper corner of the display.