There are a couple of great sites where you can learn how to pretty them up - Treadle On , Needlebar. Lots of info there on restoring them and their cabinets. It does not matter that your decals are worn, that is part of the patina of age. Just never put methylated spirits, or kerosine, or WD40 on the decals as it removes them. They love sewing machine oil so you oil them inside and you can clean their silver parts with Autosol, a car bumper bar polish. To see what can be done sewing wise look up Damascus Jane on Google, she runs a whole business treadle quilting with treadle machines, amazing lady. Hope all that helps