180 is really low... I've had them not even hit the stall until they get to 200. Brisket /is/ a tough cut of meat until it goes through the full transformation that occurs when you smoke it all the way through the stall. There's a lot of tissue to break down and that's what the stall is mostly about. Do you have a meter where you can monitor it without opening the door? If not, I highly recommend you get one. Run a probe down through the smoke hole and just let it go. You don't even need to think about before it hits 195. After that, check that it has completed the stall. If it has then, and only then, open the door and see if it's jiggly and easily probed. Otherwise, every time you open the door you're just letting out heat, smoke, and moisture.