There are a few symptoms that may indicate your linkage is going bad. If you notice any unusual noises coming from the front of your car, or if your steering feels loose or sloppy, it's time to have your linkage checked out.
Another symptom of bad linkage is uneven tire wear. If you notice that one or more of your tires is wearing down faster than the others, it could be because your linkage is causing the wheels to align improperly. This can lead to all sorts of problems, so it's best to get it fixed as soon as possible.
If you're not sure whether or not your linkage is bad, the best thing to do is take it to a mechanic and have them take a look. They'll be able to tell you for sure whether or not there's a problem and how best to fix it.