Display Backlight bleeding on 2/3 of lcd screen. what to replace?

I bought a used 2009 13" a1181 2.13 ghz MC240ll/a macbook on ebay. Everything works except lcd appears faded out on left upper corner and right lower corner. The fading is irregularly shaped and worse on the left and takes up about 2/3's of screen. It's not that bad and the computer is useable. But it is annoying. It does not change with length of time computer used or moving screen. It did not fix with PRAM reset or with reseating display cable on logic board. Video looks fine when hooked up to external monitor. Would I need to replace whole display to fix or can I just replace video cable? Or could it be inverter board? Any more trouble shooting I should do?