Well, the Machine tracks...
... well for a start, they go to the cargo bay entrance. They must have shifted the cargo out through zero-g to their ships, as they were not attached to the cargo bay (which you believe is because the cargo bay was too easily defendible if their attack started there).
Which means, because the tractor parts came in standard crates, that the lifting equipment they brought was too big for the ship corridors. Slightly inconvenient for them.
They must have been carrying a lot of them at a time. In fact, that makes sense, because the volume of tractor parts needed to make this weight would..
... volume...
They couldn't POSSIBLY have fitted that many tractor parts inside this cargo bay!
This manifest is nonsense. The weight HAS to be accurate, because of fuel considerations. It can't have been tractor parts. Tractor parts filling this cargo bay, of the type the manifest describes, would be.. half the listed weight?