aside from a broken gear,,, wouldn't a wore out plunger dump too much oil?
Oil Pump Output Test
For this test it is necessary to use premixed fuel (40 to 1).
Use a one gallon can with a hose connected to the inlet of the fuel pump.
Disconnect the oil pump output lines at oil pump.
Install separate oil tubes to each outlet and place end of each in a separate container.
Start engine and run at IDLE SPEED (3000 RPM) with OIL PUMP LEVER WIDE OPEN.
Measure the output of each tube in a calibrated glass tube.
Correct output from the tube to the crankcase should be 3.35 to 4.06 cc per minute.
The output from each tube to the cylinder fittings should be 1.68 to 2.03 cc per minute.
Replace the oil pump if output is below these specifications.