I had a problem yesterday.  I have one sharpie and it quit working!  I called my mom to tell her about it because it seemed like everything was going wrong!  It was just one of those Mondays.  She told me to put the end in hot water and it would release the ink and make it work again.  I did and it worked!  I simply put it in the water for a bit and then boom it wrote again.  It hasn't quit again yet.  When it does I will keep you posted.  Sorta neat and wanted to share!