All Small Six 1966 200 CID - Rocker Arm / Valve Springs?

[Mattsmall1972]

Hi all - I am the new owner of a 1966 Mustang rocking the 200 CID inline 6. I noticed a ticking noise from the valve train and removed the valve cover. I manually checked each valve and all were tight except one, shown in the media below. My question is: does this seem like a rocker problem, a bad valve spring, something else, or is it normal and I happened to catch this valve at a time in the cycle where it's loose?

Thank you!

 

[Slickster]

Partially collapsed lifter maybe, side movement not an issue as pressure on valve train keeps it in line...