Hello. I am going to field this one. I do not own a WSM but I doubt the others will disagree. No on the seal kit. Too expensive. When you season your smoker run up the temp. Add your chips or dust and get smoke going. You might even spritz the chips/pellets/dust a little to produce more smoke. Look for the leaks. Mark those leaks. You can buy high temp silicone sealant in a tube for probably less than that kit. If nothing else look it up on that well known auction site. Seal the leaks and maybe test run a second time to ensure all is sealed. Good luck.
New 22.5" WSM owner here. I considered buying the same thing until I did my seasoning run with a damaged door that Weber is replacing. The door was leaking like crazy due to 1/8" to 1/4" opening all along the top of the door (was 1/2" until I bent it). There were lid leaks that will seal with buildup. Even with the bad door I did the seasoning run, no water. I had no problem holding the temps I wanted from 350F all the way down to 225F. Ran for 12+ hours on a little less than 1/2 load of coal and I ran it relatively hot the majority of the time.
I've been out of town the last few days but I can't wait for the new door to arrive before I use my smoker. Even with the bad door I'm going to smoke a couple of shoulders or butts today, maybe a couple chickens too.
I agree with super dave. You gotta have air coming and going. I have never sealed my WSM. It puffs a bit of smoke here and there , but I see no way that it affects my cooking adversely . Relax and let it smoke. :grilling_smilie:
I have 3, they all leak when new but most leaks will seal up after a few cooks.
FWIW, the door can be bent to help reduce some of those gaps, I had to tweak one of mine a little but it was no big deal.