I usualy ride with ear plugs but today I go for a quick run with out them and I hear some sort of tick/very slight knock periodically. When I get back home I let it idle and grab a cut off broom stick to see if I can pinpoint the sound. The only thing I found was that you could feel the very front push rod tube cover move slightly as the engine ran... as if the rod had slack...the other 3 were fine.

Any ideas were to start oir what else to look for?