Here are a couple of websites that sell parts for vintage machines. I ordered a belt for my cousin's treadle a few years ago.
http://sewingmachine221sale.bizland....re/page90.html
If the machine has a belt, you can take it off and measure it to order from this website:
http://www.tandtrepair.com/Motor_Belts.html
Most of these old machines had very standardized parts, so you shouldn't have any difficulty fitting a new belt.
Just read some of the other posts; I didn't know JoAnn's carries belts!
Whenever I get an old machine, I oil all moving parts. Just one or two drops at each location is enough. Be sure to use sewing machine oil; other types are not fine enough.
All of the holes in the top of the machine are likely to be oiling holes. Plus, as others have mentioned, you can unscrew the silver plates in the back and on the left side to oil more moving parts. Check the bottom of the machine, because those parts need to be oiled too (remove bottom cover if it has one). Also remove the bobbin case and shuttle race; I wipe a film of oil on the outside of the shuttle race. If you can see a small red piece of felt in that lower bobbin area, put a drop or two of oil on it. Do not remove the felt! It is there intentionally to hold oil.
HTH!