Mighty Mouse scroll ball not working

All the sudden, it just stopped scrolling up. It can scroll left, down, and right, but not up. It feels weird when I try to scroll up too. How do I fix this? It's extremely annoying.

turn it upside down on your mouse pad and move the scroll ball around. this happens to me except it wont scroll down. i also find the occasional wipe down with rubbing alcohol on a q-tip works well too. theres a how to someone on here but i dont wanna look for it. also search on youtube or google.