my son has a duplo pullback motor
this motor does not work well. after pull back it forwards 2 and a half wheel turns and stops. there is a small resistance. forcing it forward two millimeters it makes a louder click and then the wheels rotate again 2 and a half turns to stop again. after forcing 2 mm it continues again and again until the spring is loose.
As there are no screws to open it and fix the mechanism I don't know how to open and fix it.
Can anyone give a tutorial to open it non destructive and fix it?