The url shows the unit. (scroll down)

Changed the filter about two months ago, the large o-ring today.

Recently it started leaking. If you remove the cup and replace it, it
seems to work fine (no leaks). Then after about two glasses full, when
you depress the dispenser lever it makes a noise like a sudden breach in
an air line and the water gushes out over the edges of the cup and
continues leaking over the top of the filter cup. Obviously past the
large o-ring but what could cause this sudden pressure and breech of the
large o-ring?

Had the fridge for years with no problem other than the ice maker
freezing up once. TIA for any help.

http://tinyurl.com/66ekzb