How difficulty is it to do a valve adjustment on my 96 FZJ. I get a little rattle at low RPM's. I've gotta replace the valve cover gasket so i figure i should take care of that. The 80 has 183K on the Odometer it has a couple of leaks but other than that runs great. I'm sure she is probably overdo for an adjusment. Does the haynes manual have good instrctions on how to do it? Should i take it to my mechanic?