How can I fix my Compaq laptop power socket?

How can I fix my Compaq Pressario R3116EA laptop power socket. It works if I wedge something under the power supply plug but this may not work forever.
I have tried removing several screws on the underside but this does not seem to release the casing. I do not want to risk using any force which might damage the casing or the 'works'.
I feel that I probably could fix or replace the socket if I could just get to it.