How to physically see and feel a bad roller lifter

Hey guys I got a tick on my driver side on my 5.9 magnum, wasn’t there until I started driving it after a hour. I pinned pointed it to the driver side rear lifters cylinder 5/7. I have a extra set I wanted to ask how could I tell right of the bat these are the ones making noise?

Would they compress easy, with the rockers still on would there be play? Etc.

Thanks!
if it's collapsed or flat wore out you could compress easily or there would be a ton of play. have you popped a vavle cover to investamagte yet?