Almost no oil pressure help

The next one is not so much fun. There's a long tall oil passage which starts at the top of the engine at the oil sender and goes all the way out the bottom, if the main bearing cap is removed. However, there is supposed to be an oil plug "in there." It's a press in plug like a tiny freeze plug. You can tell if it's in there by removing the oil sender and sticking a straight wire like a gas welding rod down there and measuring how far down it goes. I'll have to search and find out what that measurement "is"

I was thinking about that and the well maybe that passage way is just blocked and I'm not get pressure to the gauge because of that....

My initial thought was to pull the pan and take off the pump and I'd be able to see it? Or not...

Any point to trying to replace the pump?