Hello, the 50" mower deck on my Cub Cadet 1050 threw an idler pulley. This is the pulley attached to the arm that has the spring on it. When looking from the rear of the deck, it is the pulley on the left side. My question is this--when i replace the pulley, which side is up? Is it the side with the little black nub sticking up, or does that little black nub insert into the hole on the metal arm? I would appreciate any help you can offer. Thank you, Mechanically Inept Jim