Something needs to be going under these tabs (See photo)  to lock the door closed.
Again, I haven't worked on a slant top in a decade so I'm throwing this idea out...
Open the main front hatch, then close (or hold) the cash box outer door shut, then close the main door.

Hi Dickie9876,

Did you get this? If you are still monitoring the nlg site and have the Games of Nevada slot, can you please respond to this email?

thanks, lance

Thank You, Learning the terminology is a big part of understanding these concepts.

Do you mean the outer door that conceals the cash box, or the actual cash box door? If it's the cash box door, you can install a thumb lock... a keyless lock. I have that on mine.
I don't remember how the outer door latches. I'm guessing it interconnects with the main front "hatch."
Maybe another member more familiar with slant tops (mine was jettisoned years ago) can respond with more details on that.

The hopper switch is typically "locked" in the correct position. Looking from the frontside the switch (by the Molex plug) is in the right position for the black optical switch and left for the gray.