Originally Posted by
Roelof
It is called a return spring, there are several topics to find about the same subject.
There are official springs to find, like HPI and Kyosho has them. Some people use the 1st piece of a baloon, others use a hair band but basically any spring/band can work if you can make it fit.
Ended up using my fiancé’s Ouchless/scrunchi hair ties doubled over. It’s oretty efficient and I have a ton of them