Check valve is in the filter body side on the bottom.


https://www.ebay.com/itm/233320192907

 

Oooh dang I didn’t know it was serviceable. I have replaced that and it is currently in good condition.

 

That's what I was referring to with the oil check valve, yes.

Regarding valve clearance / lash, no that is under the valve cover. That'll make a TAPTAPTAP or CLICKCLICKCLICK (depending on how you hear it) from the uppermost part of the motor.