My favorite quilting machines are my 15's - I hope you love it as much as I do. :)
Personally, I would take off all the electrical components and replace them, just as a matter of course.
Jenny at sew-classic.com can replace the motor, foot control, light and cords for about $70-80 and everything will be
safe and reliable when you're done. The motor will be quiet and strong and the foot control will be much more sensitive and less fatiguing to your foot and leg muscles after long periods of sewing.
I admit to being completely paranoid about old wiring. So far, I've only gotten tingles from one of my 40's machines, but it could have been a lot worse. I guess I'll be a fire chief's daughter until the day I die. ;)
These old machines are easy as pie to work on and you may find yourself with a new obsession. Parts are easy to find and quite cheap and it's so much fun to take a gunky, grungy hulk and get it singing along, again. If I were closer to you, I'd be happy to help you, but you may have another machine freak near you who will teach you.
Tools for Self Reliance has a fabulous collection of tutorials for cleaning and adjusting model 15's. (and several other models including the 201, 66 & 99)
http://www.tfsr.org/publications/tec...achine_manual/ - one of the best resources I've seen for refurbishing sewing machines.