Some cleaners work without damaging letters. Pledge will probably work. I've used car wax on old machines with a nice result. Be careful if you use old car wax. It could be abrasive. Just guessing the newer stuff wouldn't be. DON'T use 409. It's famous for taking words and numbers off of stove parts, and may damage them on other things. Test any cleaner on a small area first.

Depending on the condition of the bottom metal, I would do a quick once over with a wire brush, just to make it hold new paint better. It can be spray painted or painted with oil base (alkyd) industrial paint, which will hold up much better than spray paint. If you find the paint you need at a Habitat Restore, it will be about 70% less than the price at the hardware store. Hope that helps. Linda

Go to the link I'll give you below and follow the directions there. I'd also recommend that you spend some time at the site looking at other stuff, too. It's far and away the best site around for information on using treadle sewing machines.

Annie

Here is a link that might be useful: Treadle On sewing machine cleaning pages