If you don't have any decals try a little Dawn dish soap on one of those Magic Erasers. Smear a little on the machine with the eraser or your finger and let it sit a little. You could also spray some window cleaner on a rag and dab the machine with it and let it sit. Then spray it lightly and wipe down. If you see it drip a little color you know it's doing it's job. Often just the damp eraser itself will work. The dirt on the machine is usually just body oil.