If you already have a core change key, or we've just sent you one, then you don't need the coffee stir stick. Just follow the same process you see here.
The lock core is held in position by the sixth "wafer" the one farthest from the front of the lock core. This is called the "core retaining" wafer. Usually the problem is that this wafer wasn't fully locked into position. This is fixable using this procedure.
In rare instances the spring which pushes it into position is missing or compressed. In these cases the last wafer will feel very loose. This you can't fix with this method, and we have to send you a new core.