Dear ?
You may not need to replace anything.
With the engine at operating temp. re-adjust ALL the valves following the instructions in any Motors (automotive) manual.
It is exteamly important that you tighten one full turn past 'zero' lash.
If the problem persists, check the pushrod carefully. Sometime they get pluged & wear at the rocker arm end. If this has occured, replace just the rocker/rod involved.
Good luck.
