Possible bad lifter

Can a lifter go bad without wrecking the cam? My engine is a 75 360 with stock crank and pistons and an unknown cam.
I have a tick from 2000 to 2500 rpm, maybe higher but the exhaust drowns it out so I am not sure. It only happens when up to180° operating temperature.
Last sunday I popped the valve covers to check the pushrod and rocker arms hoping I could find the problem. Never found any bad components but 1 rocker on each side seemed to have no preload. They were quite loose compared to the others.
Would these lifters be wasted?

Cley