I have not worked on this model, But I would buy a mechanical gauge and watch the oil pressure at different RPM's and compare it to the warning light and specs. Many engines can vary their oil pressure depending on the rpm. Some engines like Detriot Diesel 6-71 or 8-71 idle with around 5psi sometimes even less but run with 30 to 60 psi. This quite normal. Do you hear any unusal noise from the engine.Valve noise? Knocking from the lower end of the engine?Electrical gauges and senders can vary greatly. They are affected by voltage and their grounds. I would also check the simple fixes, Change the oil and filter with the known proper style filter (a quality filter, NAPA, WIX, Baldwin etc) and quality brand and weight of oil. Who knows what the unit was serviced with before you bought the tractor. Good luck. Let us know what you find.