I'm writing this to the newbie coal burners here just to point out how experience is your best tool. In shaking down my Harman TLC-2000 today I couldn't get any red embers to fall into the ash pan but, being in a hurry, filled the stove up with fresh coal anyway, just leaving the small flaming section undisturbed. With the ash door wide open, I noticed that the stove temp was not climbing & that the little flaming area was not livening up. (Years ago I might have panicked & tried a bunch of things to save what looked like a dying fire) What I did was just leave the stove alone! After about 40 mins with the ash door wide open , I had a roaring fire again & was able to finish shaking it down, top it off & I'm done.
The lesson here is when in doubt...leave things alone! (You have a better chance of smothering a salvageable fire by playing with it than just leaving it alone)