Bob... I just went back and reread all of your posts. I have some observations and some questions.
First you never really answered the question about your out fires. Is all the coal burned up or is the fire just going out. The answer to that question is very important. After you have had to clear out the boiler and start it over, was there significant coal unburnt?
About shaking down the fire. You made a statement something to the effect of "shake it down until you see a glow in the ash pan, right?" The answer is no. Burning coal in a boiler like this, you are going to have to remove alot of ash. When you get ready to shake it down, you need to take a poker and push the fire bed down manually. I would poke it down in at least 6 or 8 different spots. You'll see and feel the coal bed go down. Then shake it. The Harman grates will travel too far and you can easily dump too much live coal so the method several have mentioned here is short choppy strokes. Do it until you see live embers dropping in the ash pan. Not one or two but until you see live embers dropping under the entire coal bed. Then load that coal to the top of the fire brick and mound it up on top. Someone said 80# would be typical for that boiler.
Questions and comments about shorter seasons relative to others who may be using that boiler are irrelevant. Right now your season is 24 hours. Once you get past that mark, then I would worry about how much coal you might use in a season. By the way, what part of the country do you live in?
If you haven't already, I'd drop the domestic hot water temp down from 140*. That's way too hot and unnessecary. Try it at 120*.
Even if you burn 80# a day, it's got to be way less expensive than using oil. By the way, i think yoou may have oversized the boiler. We'll talk about the firebox reducer once we get these other problems cleared up.