Same problem as lots of other users: I'm missing one gearbit although running twice through the whole map with a video guide -_-

My question is: say there is an enemy that drops a bit and it fell down a cliff the first time it got killed so I missed the bit. When I now replay the section and everything has respawned, I have to kill it again to see the gearbit drop, right? So if it falls again I could miss it again.

If so - I could re-enter every single room with gearbit-drops after finishing them to check if bits were gone missing, so I would be 100% sure I didn't miss oney correct?

Thanks

Edit: I'm on PS4 so no upload tool possible for me