Trackball problem

[snahrck]

Ok, it never worked very well but it usually would allow me to move the cursor in all directions, but now it is not moving to the left, as long as I scroll it several (I mean, SEVERAL) times.

Anybody knows if it is worth to open it to see if it is dirty or somethink like that (it is out of warranty)?
Anyone already had a similar problem with the trackball?

Thanks in advance!