If you ever unscrewed the Moondrop and the magnets popped out you should know the right way to put them back. It is crucial part for Moondrop to work properly and achieve the necessary sliding speed.
Inside the Moondrop tube you will find 5 magnets- (2 longer ones and 3 shorter ones). The magnets should go with the same magnetic fields turned to each other (+-)(-+)(+-)(-+)(+-) so that they resist each other. This means that the last magnet will go inside pretty hard. The one thing you should note is the two longer magnets are supposed to go at both ends.  

Below is the full demonstration video ''How to put back the magnets''. Follow the video very carefully and you will get the perfect result.

Please note!!!  Be very careful with the magnets as they are very strong and fragile so they can chip off when hit each other. Better do everything slowly.