We have had a struggling ficus in a large pot indoors for some time. The tree does not really grow, but it doesn't die, either. It loses otherwise healthy leaves at a somewhat faster rater than it produces new leaves. I say "otherwise healthy" because most of the leaves have a distinct covering of whitish spots. On closer inspection these spots are actually cone-shaped with tiny brownish peaks, and they can be rubbed off the leaves with one's thumb or finger. I have posted images of the problem here:
Any ideas of what this is and how to fix it? We were silly enough to move the tree to another room where it sits in proximity to Wandering Jew-type plant and now the spots jumped there, so they are not limited to ficus.
Any help would be greatly appreciated.