How many times have you opened it to check on the brisket?
Each time you open it adds 15 minutes to the cook in my opinion :)
Also you said you are cooking some other things so did they require you to open the lid a bunch of times?
How many times in the last 6 hours have you opened the smoker?
When you open the smoker how long does it stay open?
Have you ever cooked anything 4 lbs or bigger like a pork butt?
Dont worry man your brisket will take time, you cant rush BBQ, unfortunately hehe
Now that is has been an extra hour I might check on it every hour or 1/2 hour to see if its climbing. You are in the stall stage of a brisket. Look it up if you want more info
Either way man just relax and let the smoker do its thing :)