I have an OS 46ax which I havent used in almost 2 years. Last I used it, it wa relatively new, about 6 months old. In preparation for one of my winter builds, I was looking through the exhaust port and noticed some grainy particles sitting on the piston head. So I decided to take the engine apart just to cean it all up before I ran it again. Well this is what I found - see pics. I dont have engine rebuild experience other than basic reassembly, so dont really know if its anything to worry about. Seems like very light corrosion on the back plate, crankshaft and rear bearing. How can I correct this? Could I just sand down with very fine sand paper or dremmel, would I need to replace? Any help would be appreciated. Im assuming the rear bearing will need to be replaced.