I see @TaranMayer and their guide, however that wouldn’t work on my robot. I have the 448x lock, but reverse. It extends out a lot at maximum making it unable to grab a cube. When it’s straight with the arms, it can grab them with that compression fine. Attached are pictures. 
Increasing intake compression all the time
Also, I want it to function well without rubber bands
Also, the collar isn’t supported on the sides