Hydraulic Valve Lifter Stuck?!!

[dom14]

Hey Guys,

Please have a look at below video and tell me if that looks ok.

https://www.youtube.com/watch?v=IB_w...ature=youtu.be

The first one moves freely, but the second one is stuck.
If I'm correct, it's the hydraulic action(valve clearance) that is affected by the rigidness
of the second(right side) valve lifter.
I tried turning it & tapping on it to loosen it up, but no good.
That stuck lifter belongs to the 1st cylinder exhaust valve.
All the other lifters are moving freely as it should be. The above one is the only one with
the issue.
The cylinder head is my spare cylinder head(RB30).
I have it on a bench.(I'm doing some work on it atm to make sure it's all good and ready).

Is the above lifter fubar? Do I need to replace it or is it possible to get it unstuck?


Thanx

Dom

P.S. I couldn't turn the cam shaft by turning the cam shaft sprocket. It was pretty tight. I had undo the valve lifter holding bolts to be able to turn the cam shaft. I'm not sure why yet. I'm thinking the above stuck lifter is the reason?!!

[dom14]

What if I soak it in WD40 overnight? Would that be able to get it unstuck?