If you are using NZBGet or a similar tool, look for associated .par2 files. These are "parity" files used for automatic repair of damaged RAR parts.
Compare the size of Part 10 to the other parts. If it’s significantly smaller (and isn’t the very last part of the set), it's likely an incomplete download. Download part10 rar
Ensure you are using the latest version of WinRAR or 7-Zip , as older versions (like UNRAR 4.10) may struggle with newer compression methods. Unpacking isn't working - NZBGet Forum If you are using NZBGet or a similar