Repair headphones?

So long as you are careful and remember what goes where as you take them to pieces, you lose nothing if you find nothing wrong and have to put it all back together.
Whether you can get them repaired economically depends on the model. You can buy Seinhauser's for under €30 and there is no way that it will make sense to get something repaired if you can replace it for that price. On the other hand if it is a €200 pair it might make sense to try.