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.

I believe it's ready to play mode. Replace the coin in the coin comparitor and try playing again.

Thanks SOO much for the response!
Ya, when I turn the Reset Key on the Right Side by the Handle - the machine does do some type of a "Cycle",
the display screen goes BLANK,
does some type of COUNT DOWN,

and then goes right back to flashing C.O.L - COIN IN: 3 - CREDIT: 0   
and COIN IN: 3 - CREDIT: 0

*And when I add Quarters, they just go straight thru, to the bottom coin tray. Not in Machine. (?)

QUESTION: If turning the Reset Key on RHT SIDE (10 Times) and hitting the Reset button on CPU does not clear the machine...what would be the NEXT STEP? (if any)

Again Thank you!!!!