broken ground wire

Hello everyone.

I was looking under the cowling of the 152 the other day, and I noticed that
the ground wire from the left magneto was broken. The end of it looked like
it was frayed and burned. However, when I did a mag check I got the normal
RPM drop on each magneto. I also was able to kill the engine by switching
the ignition to off. It appears to be working normally.

Is it possible there is a second ground wire that to that mag? If I had not
been looking under the cowling, I would not have suspected anything.

Any ideas?

Matt