Can you please tell me if gear oil should be inside the middle of the gear where the upper gear cover is? I have a picture attached so you can get a better idea of what i am talking about.
Yes it will get in there and everywhere else. When you first pump the lube in from the bottom it will start to come out the vent. The plug is installed and then the bottom plug. This is where most folks stop, and if the top cover is removed the lube will not be all the way up. This is the reason after it is first used the lube bottle starts dropping and needs topped off.
The better may is after all plugs are installed, the drive is laid on its side with vent plug up. Now remove the vent plug and slowly pour lube in until full.
Another method is after it starts coming out the vent, then lay on its side and continue to pump until it comes out the vent again.
To me, your pic looks like it may have been run dry from the brownish color. This may be just lighting