Yep! That one is ugly. You need to pop the spring off and wobble the valve stem in the hole...to see how much clearence it has. AND to look at the valve seal. I'd come near betting the seal has went away.. If it has then you need to purchase a complete set of seals and install them all. If the clearance is a lot more on that ONE valve you might think of a new guide... but if all have similiar clearance then it is the seal and nothing else.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist