Well finally something that i know we had happen to our old 510 we had when we were kids. The engine oil pump has a valve for relief of the excess oil and this valve has a ball a spring and a cotter pin to hold the spring and ball in place. What was wrong with ours was the the spring was cracked and the ball was floating in this valve and would seal against the broken spring when enough oil flow was achieved and the oil would lube the motor as normal . hope this helps you but this was the problem on ours.
Thanks Rotor, that's kind of what I was thinking, something in check valve. I'm just going to hit the throttle and get the pressure going and keep running the machine.