The best way to check for broken traces is to use a multimeter with continuity check.
If you don't have one, check if the blob of solder that the switch is soldered with, moves when you wiggle the switch a little. If you can see it move, it means the trace is broken.
But I don't think this is a broken trace. More likely the contact inside the switch is dirty or slightly bent. My guess is it's dirty. In this case there are two things you can do. The first is to open the switch without desoldering it, remove the dirt, carefully clean the contacts (make sure you don't bend the contacts), and put everything back the way it was. There are guides on how to open cherry switches without desoldering. This one, for instance:
https://www.youtube.com/watch?v=HysRQnJiupQ
If that doesn't work, try to desolder the switch and swap it with another one you don't use much - Scroll Lock, for instance. Or you could buy a single switch and replace the broken one.
