cleaning the finish on a K-325 loco

White stuff on the couplers is mold release agent. The hair dryer treatment will clean up the couplers. White spots on the surface of engines and cars in my experience has been actual mold. The engines except for the lettering are pretty tough. I have removed these spots with a little Windex on a paper towel, then wipe. Stay away from the lettering. I have also used WD40 and Clorox on my steam engines with no ill effects Just put it on the towel first, not on the engine. Never on the lettering. 

Just took a closer look at the pictures. It is hard to be sure but that could be paint failure from long term storage in a high humidity environment. The spots look different than the mold I have seen develop. Were it mine I would try some WD40 in an inconspicuous spot but I am very reluctant to recommend that based on pictures. The lettering on that engine looks perfect. 

My 314AW had this problem. I cleaned it carefully (mild soap and water) and then using a toothpick and some matching paint carefully daubed the "pimples." The results aren't perfect, but much better looking than it was before.