A quick test of a valve guide is to grab the valve spring and try and move side to side, if its loose you will feel it. With the weak valve springs, you might also try and twist it while holding down on it. I'm not sure you will get this done, but you might be able to.
A sticking valve sounds like a high pitched sqeaking till it locks up all the way!
Sounds like the next step is to remove all the rockers and turn the motot over to check for noisy.
Joe
