2010 Chrysler 300S. Misfire #5 cylinder. Rocker on rocker arm moved forward. Caused leak in #5 exhaust cylinder. Had 79K on car. Fixed and reworked head, completely new rocker arm assembly. 20k miles later same cylinder with leak. Except this time the one rocker slipped backwards. Wore into bridge.
any ideas what would cause original factory rocker to move and then again after repairing??

Shows both times rocker moved.

 

What work was done to the head?

 

the slipped rocker caused exhaust valve to seat with a small gap which caused miss fire. Valve was redone so exhaust valve seated correctly and new guides on exhaust valve rods. Worked fine until rocker moved again

 

was the head checked for being warped?

 

I’ve seen many post throughout many sites of people with the same problem with the same cylinder. Yet Chrysler acts like they’ve never heard of the problem.