The classic treatment for mold is to brush on or spray on a mixture of 70% ethanol in water. Just in the off-chance that there is some coating on the piece that might react, dab some of the mixture using a small brush or a swabon a spot and let it dry. The ethanol/water mixture is the active ingredient in Purell, and is the remedy recommended for artists whose works got moldy after hurricane Sandy. As a conservator who has treated a lot of moldy objects, I have not ever seen damage from this treatment – and it works!
