tightening valve tappets?

[KNanthrup]

Hey guys, it seems I've been getting some very excessive noise from the valvetrain and it's been going on for a pretty long time getting slightly worse, and I just pulled the valve cover. Everything seems to be in check except I have a little play in the rocker arms. Not much play, but if i wiggle it back and forth a little i can sort of re-create the sound i hear when it's running. I think that all I need to do is tighten them up against the valve a little bit until the play is gone but I see no adjustment bolt or anything to use (I'm used to working on Chevy's). Can anyone tell me what I need to do to snug them up a little? Is there something I am missing or are they non adjustable?

Thanks