Lid fails to open!

I'm using Sony DRX-810 UL from 3 years and it's being working fine...but recently from past few months it has problem with it's lid......when i press the button to open up the drive nothing happens, just a sound of a jerk and nothing happens, so keep pressing it again and again may be 20 times it opens....now this pressing continously happens everytime i used it. This is so annoying!
I opened the drive with screwdriver to diagnos the problem and wat i found that when i pushed the button the drive is not capable enough to push back up to the extent where the tray pops out so with the slight pull of my finger it comes out with a single push on button, now could u plz tell me what should i to repair it....my drive is still opened on my desk...and dont know how to give that force to the drive for the proper push so that the tray comes out in one click.

Waiting for your respone.
Tushar Srivastava