Step 1:
Remove the throttle mounting piece from the display by loosening the 3mm bolt (left, counter-clockwise, shown below) to release the throttle mounting piece from the display.

Step 2: Realign the spring.
There are 2 holes where the spring is inserted. One side is inserted into the lever, and the other side is inserted into the throttle mounting piece (ensure that the spring is firmly pressed into the holes),
also check that the magnetic sensor strip is correctly inserted in the throttle lever piece.

Step 3:
Rotate the lever and mounting piece so that there is tension on the spring, and then snap the lever, spring and mounting piece together.
Test that the spring and throttle lever can be used, and that there is spring tension when the lever is rotated; before re-installing the throttle or display on the bike.