Why has screen lost its tension?

Hello,

I am trying to help a friend repair her computer (this one) and am more familiar with working on Apple products (iBooks). The display on her T41 has lost its tension and will not remain in an open position without support.

Before I tear into this, I wanted to ask if this is a common issue with these computers. It would seem to be the hinge/clutch mechanism.

Thanks for your input. I'm in unfamiliar territory here. fortunately it looks like there is a great iFixit repair manual for the screen.