I got a machine (through legitimate means!) 
Could you expound on why "through legitimate means" was necessary?
 
,  It's just that posting a thread titled 'how to get past locks' might make people edgy!  I actually traded an OutRun upright for this machine, and the guy I got it from no longer had the keys to the doors.  The back door is just held on with screws, so I can reach the locks, but I was kinda wondering how to get into the coin catch, because I cannot access that lock from behind, only the coin door lock.  Funny thing was, after putting his new machine in place, I handed him the original owner's manual for it, and he said 'Wow! what a gift!  I never had the manual for this machine!'  Then later, I opened the back door and the original owner's manual for Cyberball was laying right there... 

  So, I almost thought the keys would be zip-tied to something back there  

Name of machine and picture please. Some dedicated machines had keyed alike back door locks.
Hey Ken!  It is a Cyberball 2072 2-player upright.  I dont have a picture of it here at the office, so here is a link to a video of the actual machine.  You cant see the locks too well, but you can get a gist of what kind of cab it is.
And incidentally, here is the video for the Donkey Kong cocktail machine that YOU FIXED!  Thanks!
(& it has since been degaussed!)