Wow. I'd have to play with all that linkage adjustment to make sense of it, things sometimes work opposite of what a first glance would look like.....
Disks would come with and work best with the same size blades front and back. Likely your disk would work better with new blades on the rear. When folks try to save some money, they put the biggest blades on the front where they do the most good, and leave smaller blades on the rear.
Weight typically does best on the front gang first. I'd suggest weight on the front like you put on the rear, and figuring out how to angle the blades more.
Be aware tho, more weight makes the disk work harder, and rock damage, and overall wear adds up faster with weight. Just the nature of things.
A disk works best in soft dirt, like damp (not wet!) spring time. In a hard baked fall dry period, it's common for a disk to not get into the ground very easily no matter what you do.