I've fixed this twice now. How do I modify my original published project? Are published projects immutable, even by the original author? Should I just publish the revision and delete the original that has errors?
Hi, there are two thing happening in your model. First, propeller blades aren't connected to the center. You can see this if you try to move faces where it should be connected. You can fix this by using 'mesh tools' (hammer icon, or 'J' key) and using 'weld' - this will merge points that are close together. Second issue is caused by lines that have more than two faces (there is probably a face inside). You can fix it by using 'draw lines' tool, which has side effect of creating faces where possible, which in this case fixes this problem.
There is also some visual problem (gray pattern), which I have no idea what causes it, updating GPU drivers might help, or contact support if it doesn't help