My dx6i came with a gimbal centering kit
and the two types of metal strips
th
the smooth one is for the spring kit,
there is also how to you tube videos or you local rc shop should be able to do it, but most people usual have one spring loaded,
Also in the dx6i manual there are instructions for changing a mod 1 to a mod 2 and vise versa so you can have the spring stick on the side you prefer when you go into the program settings
Cheers Tracy