K5synth

Hi,I have recently got hold of  K5 keyboard version and the backlight is only illuminating part of the LCD.It is about three quarters of an inch thick and runs the length of the lcd.The outer parts of the lcd are not illuminated.
Is the backlot shot or is it the converter?I cannot hear any high pitched whine that people mention.
Some of my buttons are not working-I suspect they need cleaning.
K5=awesome synth.I love it.In this world of analogue madness the K5 is like a breath of fresh air.
Thanks,
Steve