[Thin walls no slicing]

Yeah, if I drop the line width settings all the way down to 0.1mm I get this instead. Really not an ideal solution because the nozzle is still printing 4 separate walls and then filling in the gaps between them. I've seen this gear printed (bought them on eBay) but I don't understand how they're being done. My guess is that it's a redesigned gear.

[Thin walls no slicing]

I did try the "Print thin walls". I'm using a 0.4mm nozzle, but this appears to be a slicing issue, not a printing one. I'm new to this - is there a way to tell the slicer what nozzle size I'm using?

[Thin walls no slicing]

I'm trying to print a gear I found on Thingiverse that has some very thin walls. There is no mention of this being a difficult issue to address, but I've tried every setting I can find in Cura but am unable to solve it: