Science Buddies: "Ask an Expert"

Hi, My son is building a jumping robot for his science project.
He has followed all the steps mentioned in the below article, however the robot is not jumping. How do we trouble shoot.

https://www.sciencebuddies.org/science- ... #materials

Thanks,
Maithili

Hi - it can take some tinkering to get this project to work properly - there are already some suggestions in step 12 of the procedure. Can you describe in more detail exactly what is going on? i.e. is the motor moving up and down on the legs, but the robot is not jumping and getting off the ground? Or are the bottle caps just slipping against the dowels so the motor never moves up and down at all?