Hit both balls with 320 grit today and it was like a sand storm. I wet sanded it after awhile. I got most of the surface scratches out. Only the deep ones remain. Likely, it was drilled for a right hander and most of the track is away from the left. There are some though..might have been used by a lefty at some point. Anyway, going to have them plugged in the summer and I am going to practice with them. What a tandem!