Hi, I have a Kohler 13 hp engine problem.found intake rocker arm broke,intake valve stuck,pushrod still straight,valve not bent. I freed up valve, checked valve seat,cleaned and assembled.I put a used rocker arm on,just tightened it because it's hydraulic cam,right? Bright blue spark,shot of gas in carb, won't run.Is there more to the valve adjustment?compression seems low. thanks