MacBook :: 13" Backlight Off When Fully Open?

I have a 2.2Ghz MacBook recently out of warranty, and now the backlight turns off when the lid is fully open. it's fine till about 55-60 degs but i can't open it more than that, backlight goes off. at a certain angle i can wiggle the screen and watch the backlight flicker on-and-off. if it opens too far, closing it to about 35-40 degs turns the backlight on again. then i can nudge it up to 60 deg again. the working angle also seems to be more acute when the mb has just been woken up, the backlight turns off at around 40 deg. but after it's been awake for a while i can open it up a bit further.

so anyway, i read this issue is quite common with the rev.d macbooks due to an inferior display cable used so i opened it up, using the iFixit.com guides, hoping to see something obvious i could fix but everything looked ok. i stopped short of removing the LCD from the top cover, but had a look at the inverter board. since there's nothing i can see with the naked eye, the only way to troubleshoot now is to start replacing parts one-by-one and seeing which one solves the problem.

i don't think it's the LCD as the display is fine when the backlight is on, and i can still make out the picture when it's off. so that's one expensive component i'm hoping to avoid replacing.

it might be a cable needs replacing but which one? the one that slots into the right hinge looked alright but i thought it might be getting pinched as the lid opens? maybe an internal break in the wire? is there another cable behind the LCD screen i should check also?

i know if the LCD was off all the time then it's probably a faulty inverter board and would just change that but could it also cause the problem i'm having? it seems strange that a circuit board would choose some arbitrary angle to work and not work. this seems more like a mechanical fault than a logic-based one?

and lastly, the worst thing would be a logic board problem but again, i don't see how this could be? any repair gurus care to advise?