Sounds like the ribbon has come loose from either the logic board or the display. You probably could fix it yourself if you are really technically able, but it would be fiddly and is probably best to just take it into the Apple store.
Do not mention that moving the hinges or pressing on the casing temporarily fixes it, they will probably try and blame the issue on you.
it is 10 months out of warranty!Ok thanks guys! How much do Apple change for things like this?
I'm not sure. But its expensive. Just take the bottom case off, and reseat the display cable.
Check the cable (shown in Step 9) and reseat it. It that doesn't fix it, Check the other end of the cable (shown in Step 32)
Guide here: http://www.ifixit.com/Guide/Repair/Installing-MacBook-Unibody-Model-A1278-LCD-Panel/1428/1
Maybe the cable is damaged, and when you push it, it flexes to work right.