Slant Six Oil light coming on — need a new pump?

Ok, so I have updates.

First of all, my local Advanced Auto had an oil sensor socket with both 1" and 1 1/8" patterns inside one socket. Of course, the socket bottomed out before the 1" pattern actually come in contact with the flats on the sensor. My choices were to order a 1"-only socket online, or work with what I had in hand, so I got out the angle grinder and cut the 1 1/8" pattern tip off the socket. Kind of annoying..

Anyway, I got a tee on there, and plumbed in my new mechanical gauge as well as my old oil idiot light sensor. Then drained the oil, got rid of the drain back spring, and even pulled my relief valve and spring. The relief valve was very clean and smooth. But I buffed it up anyway, and shot some carb cleaner up in the orifice to boot. Bolted it back up, and mixed up a concoction of 3 qt motor oil, 1 qt Marvel Mystery Oil, and 16 oz of Berryman's Fuel Cleaner. Put a new filter on and poured in the concoction.

To my surprise it fired right up and the mechanical gauge read 50 psi at high idle (choke on)! I even bled the gauge's oil line to make sure. Also, the light did not come on at all..

Once it warmed up and i kicked the choke off, it was down around 20psi at a low idle. Yippee! I ran it for 15 minutes, drained it, tossed the filter, and replaced with 3.5 qt motor oil, 1 qt Marvel Mystery Oil. The concoction I drained was dark brown, but not overly black. I ran this second concoction through, with about the same PSI numbers. Tomorrow I hope to drain and replace with a conventional 30 weight oil.

So, problem solved! I'm very happy I didn't have to do too much. I guess my problem was either due to the busted up drain back pieces, or perhaps a bad connection at the oil sensor? Hard to tell. Either way, I'm happy..... Thanks guys!