Constant force Linear banding?

My team has created a one pneumatic cylinder mobile goal lift inspired by Team Dougie’s 1 piston mogo mech.

I am trying use rubber bands to give it a little more power so it can lift the goal up more times and without using as much power, but I am running into an issue with the banding.
The way I currently have it, the rubber bands are stretched the most when the grabber is retracted, so they give it the most power then.
They give it the least when it is the closest to all the way forwards. What I need is the opposite; I need it to have the most power when it is almost all the way forwards, or at least have constant force on it.
Pictures of it are below, does anyone know of a technique to give constant force or nonconstant force the way I need it with this setup?

Sorry if I misunderstood the post, but I don’t know what way rubber bands can be used with constant force applied. However, experimenting with rubber band positioning should give you the desired opposite effect. So, put a rubber band in your hands and just start going around your robot to see which part and your claw get closer when closing or get tighter when opened.