I wouldn't run a roll pin, too hard. Might break a prop instead. Brass was for real stumpy or rocky areas, as I was told. Steel gave a bit more strength but was still pretty soft, as steel goes. I'd carry both, and put the one that you sheared back in it til you know more. Super little motor. I had a 67, sold it to an old gent I worked with. I used a brass in an older 35 or 40 I used to have, and the torque of the motor sheared the pin. Just my past exp, I'm no tech.