I want to repair the brakes on the JD 520 tractor that I have. I got stumped right off the bat. The brake drums are larger in diameter than those on my JD 50. Therefore when I remove the retaining brake shaft nut, I cannot remove the brake drum off the brake shoes, due to not enough room to do so. Do I have to remove the whole shaft and brake assembly and then remove the brake drum? See attached pic.