I shifted the elevator a bit so you can get crates back into that room if you take them out prematurely.
Is there a way to fully reset the level? The problem I'm having is that it's not impossible to mess it up irreparably, discover this after you've checkpointed and then you have to do the whole game again to get back to the level.
I'm now up to the final section of this level (which I assume is the last one) and it feels like I might have prematurely used a crate to activate the ceiling switch in the first room, but it's stuck there now and I'm not sure if I have enough crates to deactivate the switch and get it back.