I've used the stethoscope, as mentioned; cannot isolate it to a single location. ALL of the pushrods can be spun by hand with the valves CLOSED, this is not normal?
With a hydraulic cam you should not be able to spin the pushrods with your finger tips. With a pair of pliers may be. There should be a half turn of preload on each. A solid lifter cam is different. They run clearance and not preload.
