I'm trying to fix the springtrap, if it's not an error, the mangle has an error when changing parts
actually I personally was able to fix springtrap, but not mangle.
From what I recall, there is also the piece in the room with the barrels beside the stand, by clicking on the barrels. With the other pieces, that should make the full mangle. By trash can, I assume you are talking about the dumpster in the back alley?
I had gone trought pretty much the whole map a few times clicking on everything i saw, (that's how i found out about the vent cause I didn't saw it for a few times)
..... BUT APPARENTLY NOT !!!! I swear I 100% gone trought the trash in the back alley before, and I am 100% sure that it isn't due to the mangle quest needing to be triggered for the pieces to become available. because before I was able to get into the basement I got a "mangle claw piece" or something like that.
Which is what gave me the hint of "Hmm idk what's in the basement but I'm guessing mangle is in there"
This is also what made me think that to get puppet guidance you needed to meet the mangle quest triggered since it wasn't in the puppet. But even after meeting her it still isn't there.