A lot of the Wiki is incomplete. I've gotten this achievement before so I know the location,
what I recommend is going for the Maintenance Teleporter first, before anything else, and save.
Then once you're in with Sally, take your time. Entry 19 is actually easy to find, or at least it was
for me on all previous plays, about 6 now. The difficult find is General Chase's Overcoat in the footlocker.
Since you know you're going to be locked out, and you know you can't get back in for # 19, it's easy to miss.
As you enter the U-shaped room with aliens up top behind you, the footlocker is on the floor over the rail,
to the right as you enter. That one I've missed on at least two previous plays. This time got it all again,
the coat and holotape, archive # 19, and the Samurai Sword at the end of the waste area by all the med supplies.
(Then you will have two Samurai Swords by DLC ending.) The Swords look good when displayed with the others
that I have which are Jingei's Shocksword and the Vampire's Edge from Vance.
Also the Wiki is *really* short of all the Enclave Outposts. They miss at least 3 that I've found.
As usual, whenever I add an entry to the Wiki, it gets deleted so fuck those guys.
Best bet for special areas like this one on the alien ship is just playing through a number of times.
This time I have the Child at Heart Perk so Sally unlocks that door in Engineering that I always had
not accessible. Three storage containers of loot just for asking her if she has a stash.