There are 3 white magnets in total located at the top of the cup to ensure the bending lid is fastened correctly to the blending cup. In case one of the magnets falls out, which is extremely rare but still possible, there are couple ways to proceed.
Easiest way is to insert the magnet back to its place.
If you have the magnet that has fallen out, locate it back to its place by pointing the wider end into the hole and pushing it in. Use your fingers and/or try to push the magnet in gently with a tool (for e.g. pliers or tweezers).
If you have lost the magnet contact us via email@example.com.
Reposition the blending lid.
Since only 2 magnets are ensuring the blending lid is fastened correctly to the blending cup there is a temporary solution allowing you to enjoy blending until the new parts arrive.
Inside the blending lid there are three hall sensors (as per illustration below). Try to tighten the lid onto the blending cup to a different thread position each time until both magnets present in the cup are located against the two operating sensors. Make sure the cup is closed properly every time you reposition it and test on a blender base.