This well corrected lens has only 4 elements, so cleaning should be easy. The front two unscrew easily and the rear two unscrew easily.
Though, the rear two elements look like they are permanently sealed together with a rim of metal squeezed over on of the elements. I did not see a way to get them apart. Thats OK because the inner element surfaces were pretty clean. In terms of the front elements, the front surface was the worst. It had the awful oily residue on it and it was a little trouble to get it all off. In the end the glass cleaned up pretty well and underneath the haze there were no scratches or imperfections in the coating.