A lot of the items miss mentioning the availability for 1 tower.
For example Scraps for P.H.A.T Pants, if you click on it you will see it's available in chapter 18-3, 22-7
Actually, it is also available in Chapter 24-6 with the same drop rate as 22-7. Yet it's not even mentioned in the possible drops of 24-6
Most of the gears with only 2 mentioned location have a 3rd "hidden" location that isn't mentioned anywhere in the game itself.
I have wasted an insane amount of stamina in the previous batches farming old chapters while I could have benefited a lot if I knew newer locations do include the scraps. That's vicious.
I strongly want to believe this is a bug and unintentional.