The adapter allows the gearbox to switch to 13:1 (700 rpm at 5V) instead of the original 48:1 (190 rpm at 5V). None component is destroyed and you can go back to the original gear setup.
New setup excludes the 2 last gears from the diagram. Typical torque of the DC motor is 20 gcm, the original setup delivers near a kilocm of torque (960 gcm) at 190 rpm, the new setup delivers 260 gcm at 700 rpm
Cut off 1 mm of the bottom part following the groove in the model