oil pressure disappeared.

I replaced my oil pan gaskets and windage tray due to a leak. I went with a windage tray/gasket combo that is much thinner. The pan was off for a week or so. After completion, I cranked and got no oil pressure even with the distributor off and a hex rod in a drill motor going CCW.. I then loosened the oil filter a bit and used a hex rod to prime the pump and got it to burp and then oil pressure was back. Fast forward a week and I started it and I got nothing again. This time I took off the oil filter completely and tried cranking (without the ignition disconnected so it would not start) I get nothing. Filter was new, oil fresh. Pump has less than 1000 miles on it. The only thing I can think of is the pickup has an issue.

Could it be that since I removed the gasket and windage tray and used a thinner one that it is hitting the bottom of the pan and preventing it from sucking up oil? Is there a one way valve stuck open somewhere that is supposed to prevent oil from draining from the pump and causing it to lose prime? I would think that if I cracked or broke the pickup that it would not have worked after the first incident. Is the pump bad. Is there a check valve?

Help, I need this fixed so that It never gets driven without oil pressure by anyone.