I would measure & find the exact place on the axle where the seal hits & if it is smooth I would not sand it as that would make it smaller & more likely to leak. You might check with a dealer & see if they have one of the original type drivers that has a shaft that goes inside the seal in addition to the flat face of the driver contacting the seal flat. These distort the seal much less in addition to keeping the inner spring from being potentially popped off while being driven in. I fill the cavity where the spring is with heavy grease to hold the spring in place while being driven in