hi i need to know when or how to know when the cam or rocker arms need replacing.

i have a 96 fourtrax 300 4×4.

the reason im asking its because i fixed the piston, changed the timing chain and the one way bearing and the quad still makes clicking noises. today y checked the rocker arm and the exhaust had a lot of play so i adjusted it, but still hear a noises.

do the timing chain guides need to be replaced? what happens i don’t change them?