I addressed both complaints on my Brinley. On the adjusting handle, I placed a flat washer between it and the plate. That allows the pin to clear the holes.
The problem of the debris overshooting the top of the catcher can be solved without slowing down. Slowing down tends to drop too much at the front edge of the hopper and it will create a *** and never fill.
First off, the draw bar should be parallel to the ground or maybe even a little higher. You have yours too low. Flip it over to get more range. Raising the bar changes the angle of the cowling. You can adjust how the hopper carries so as not to drag.
Also, the cowling tends to bow up in the middle and needs to be straightened. Use a thin board to avoid kinking the sheet metal.
The top flap hangs down too low and intercepts the flow of debris. What I did was to attach a length of 2" ABS sched 40 pipe to the top of the side frame right where the bend is and then route the top flap over top of the pipe.
The one problem I did not solve was the tire treads plugging and then slipping. I wish they would have used a self-clearing tractor tire tread pattern. I'm thinking that I might angle cut every tread to make it self clearing. I just haven't come up with a jig or template design yet. If someone decides to give that a try, remember that the pattern needs to be opposite to how a tractor is since the wheels drag, not drive.