Main support / handle does not ‘catch’ or stay up on my Q/vertex

Video 

https://youtu.be/ICm0PqsYsXs 

Fitting instructions:

1. Unscrew the main support clamp using a T20 TORX 
2. Remove the LED from housing and disconnect the Power button and remove the clamp
3. You can now remove the main assembly as a whole
4. Replace the new main assembly ensuring that the stabiliser is fully retracted in the vertical position and the new main support is horizontal when fitted into place. This ensures that the main support is fitted in the correct gear positioning
5. Feed the LED and power wires back through the clamp and secure the clamp in place
6. Reconnect the LED and Power switch before testing the connection
7. Screw the main support clamp back into place