while the deck plates are worn, I think your biggest problem is how worn the metal is when the stalks travel past the deck plates in the direction you drive, there should not be a big worn out triangle hole after the crop passes though the deck plates.  the faster you go the worse it will be.

that big (huge) gap is where all the stalks will break off and get jammed up the faster you go. the gap allows the first stalk to actually travel past the rear of the stalk roll and get stuck because it is no longer being pulled down. then all the other stalks next in line bunch up behind the first one.  when you travel slow enough for the stalk to pass through the stock rollers (in the direction of the ground before it can reach the triangle hole in the direction of travel, thats why it works to pick slowly

i see someone tried to build yours up with weld after it was worn, and even the weld has worn through again.  it needs about 3\4 inches of steel there at least imho.  It will amaze you at the difference it makes.