One trick, if you are not pulling the galley plugs nor taking it apart - is to put the oil pump on, temp hang the pan, put some diesel in the pan and run the pump while rotating the engine.
If you wipe the cylinders with white towels and ATF and you find gray, I would highly-highly recommend taking it all apart and scrubbing the hell out of it. A 5 gallon "Homer bucket" with a warm water + hefty dose of Dawn dish soap, an array of nylon bristle brushes and a water hose with a sprayer and have a scrub-a-dub party. The blow it out with air, empty a couple cans of WD-40 in the process with the air to displace water. Then scrub the cylinders with ATF and white towels until clean. Some fine particles will get caught in the filter. But all it takes is a little chunk small enough to make it past the pickup screen and you'll be very unhappy. Been there, fixed that - last year.
Couple of small particles from a broken spring seat cup, one which made it to the pump bypass and jammed it partially open. Had about 5 psi on the gauge when driving it into the trailer.
