at lunch i inspected the valve. as soon as i took the top half off i could tell that the "spider gasket" is the problem. there is one "spoke" that is badly stretched out and out of position and another that is stretched but not nearly as bad as the first.

for the benefit of others on the forum i attached pix where you can see that the "spoke" on the left is arched. sorry for the quality of the photos....camera phone

spider gasket 1.jpg

spider gasket 2.jpg

they have replacements for $7