I have an old no-frills WSM I've been using for more than 10 years, with no working thermometer, an access door that leaks smoke, a water pan that just won't come clean any more and vent controls that are so bent that I have to move them with a pair of pliers. In other words, I'm just getting it broken in right, but it makes great barbeque, so I have had to make some concessions.
I use an instant read thermometer stuck in the top vent to check temp, and I reduce the amount of charcoal I start with to avoid a temp spike at the beginning, so I do have to add charcoal for longer smokes. I fire up the new batch of charcoal in my chimney, then, using a pair of Ov-Gloves, I lift the WHOLE smoker off the base by hooking my fingers under the lip where the lid fits on. It's not as hard as it sounds, just do it slow and level and set it down carefully.
Then, add the charcoal into the ring, put a layer of soaked wood pieces on top of the (too) hot coals and replace the smoker on the base. You wil lose less than 10 degrees of cooking temp at the rack levels and your temp will re-stabilize quickly.