Replacing laptop keys on the keyboard.

Hello,

Unfortunately after quite a lot of use my shift key on my HP Pavilion dm4 (good laptop in my opinion by the way) has lost one of the clips that keeps to the body on the laptop seems to have come off. This means that even though it is still usable it comes falls of the keyboard sometimes when I tap it.

Does anyone know any where I can buy a replacement?

Thanks in advance for any help.