There are many ways to remove factory paint but most methods won't work for all paints. Brake fluid will remove many manufacturer's paints but can damage some plastics, as I discovered on an Atlas S2 switcher. One of my preferred methods is methyl hydrate, availaible in hardware stores. This stuff works well on Athearn, Roundhouse and some others. With care, you can use a little on a rag to remove just the lettering if you wish. Polly Scale makes a product called EASY-LIFT-OFF, which is useful for removing lettering and will also remove almost all types of paint. It is, however, fairly expensive: I have a small (8 ounce) can that I bought several years ago for about $11.00. It is extremely important to use all of these products with adequate ventilation and preferably while wearing the proper respirator. The latter two products are flammable and it is also adviseable to wear rubber gloves and safety glasses when handling any chemicals. In particular, methyl hydrate is readily absorbed through the skin and harmful vapours from any chemical are easily absorbed through the eyes. Model railroading may be fun but it can also be dangerous. Whatever product you use, you'll probably need to scrub the shell to remove stubborn areas of paint. An old toothbrush works well for this. After all of the paint has been removed, be sure to wash the shell in warm water and dish detergent to remove all residual chemicals that could affect the new paint job. I hope this is of some assistance.