64 C10 Engine Ticking Sound Help

[850_C10]

I've been trying to figure out this ticking noise on my 64 C10 for a long time now and haven't made any progress. The engine is a 1978 250 Inline six and I have put a new cam in it, new lifters, new pushrods, and even new rockers and the ticking still won't go away. I have also taken the head off and cleaned the valves and one valve does not slide through the guides as easily as the others. Could that be the problem? I am at a loss, any help is appreciated.

Video of ticking
https://www.youtube.com/shorts/hxsebdoDo-Y