[H] Microsoft Wheel Mouse

I've been using this mouse for years, I know it's not the best mouse for strategy games that requires high accuracy, but I wouldn't want to give up from it ^^

Anyways, the left click is not working properly anymore, so I would like to open it and see if I can fix it before buying a new one.

So, anyone knows how to open it? is there screws somewhere or does it open by "jiggling" it?