I think they may have renamed that smoker to the Smoke and Grill last year, but anyway, I would have to agree with BW. If you can add a bunch of air holes to the charcoal pan to allow air in, otherwise the charcoal will smother itself. I had problems with my Vertical Brinkmann until I did this. Another issue if you are having a hard time retaining heat, just remove your water pan, I used a water pan for sometime, until Jeff (007bondJB) remarked in one of his videos that having a water really does not introduce anymore moister into your item that you are smoking. Some may disagree with the comment, but for me, the water pan did nothing. You are better off covering it with foil and putting some heat retaining rocks in it.
A nice trick that I saw on youtube relating to your type of smoker is, if you have the 3 metal legs on the bottom that you set your fire pan on. Take those off from the inside and place them on the outside of the smoker. This gives you free access to your charcoal pan so you do not have to keep opening the door to stoke. Yes the pan will not hang in there but all you need is a brick to place under the pan.
Hope some of this all helps you out some.