Sharon,
Some of those plastic lights are screwed together and can be rewired. I believe all the old metal lights can be. The current ones as sold by Sew-Classic and others are just glued together. If the wire goes bad or the switch wears out, toss and replace.
I had to put a replacement on my 202 because it didn't come with a light. In the pic above I have a Singer fish eye light on it. That was replaced by one of the current ones I described above.
I wouldn't worry too much but if you can find an older one it will complement your machine better.
Joe