If you've worked with a certain major brand of wood glue you have probably run into the dreaded "glued on top" phenomena. No matter how persnickety you are about cleaning the outside of the top, there's always glue trapped between the "pop-up" spout and the fixed part of the top that semi-hardens, just enough to make opening the top a job for magilla-gorilla.
One fairly straight forward fix is to cut an acrylic disc, like I did at the Techshop, http://techshop.ws, to fit under the top's ridge. This gives you a larger area to grip and pull up the top. But, the lower edge of the disc has a sharp edge, left from laser cutting.
Wouldn't it be a fine thing if the edge was beveled? Well, my friend, read on!