Ok, I can explain how to use the draft control.
Once you flip the doo hickey, drop your implement into the ground, then adjust the draft control lever forward for deeper or rearward for shallower.
When plowing, or in my case, using the rippers, draft control keeps you from digging in too deep. It also keeps you digging in deep enough.
Im using 6 rippers in fairly hard soil that has a good covering of bermuda grass. That seems to just be enoigh force to make the draft control work.
So in your case I dont think the rake has enough force to make the draft regulator work.