Review the oiling system diagram in the service manual, and familiarize
yourself with it.
the oil is sucked out of the crankcase to the pump through a screen in the bottom center of the crankcase.
as it goes through the pump it is directed thorough the passageways and excessive pressure is controlled with the pressure relief spring & ball.
If someone has removed the front cover ( pto side) it is possible that the relief ball is missing or the spring is broken.
First I would remove the electric pto, then front crankcase closure cover.
That will expose the pressure relief spring and ball, and determin if it is in the proper place.
if they are there and ok then proceed to the 4 screws holding the oil pump cover plate on and inspect if all is well there.
That is the extent of the external accessible parts.
When you get that far I will help you further.
Hopefully you will find the problem.
it is possible the big plastic drive gear is broken inside the crankcase or the thin roll drive pin, but it is very uncommon, and requires splitting the crankcase halves.
Do you have a divorced oil filter? ( hoses connecting it to the engine)
or is the filter attached to the engine?
