Hey OPS, are you getting a better 'feel' for the shaking yet? I think once you learn t 'feel' the coal bed through the grate handle, you
will have more success.
Remember that what you are trying t accomplish is to open up air passageways in the bottom of the coal bed.. the coal burns from the bottom up,
so as the coal turns to ash, it clogs up the air passageways. The ash settles on the grates, and very little falls through the gaps..
So even a slow opening or tilting of the grates will cause the ash to slide off it's resting paces and go through the gaps.
Just don't open the gaps too far, or you will have pieces of coal jam in the gaps.
You can 'feel' the coal come in contact with the grates.
On Harmans, the front and back of the grate system tends to get clogged up with ash, this is because the front and rear grate is adjacent to the wall or firebrick of the burn pot So in the center there are two grates next to each other, everything is moving when you shake it down, but at the front and rear there is the stationary firebrick and one moving grate, so more ash tends to stay put..
The bent-poker is the best way to dislodge this ash,, go through the ashpan door and 'floss' between the teeth of the grates at the back and front,, you will have cascades of ash fall down once you open up a passageway and agitate it a little
You can tell when the front and back of the grates are clogged, the fire will be dark in those areas, because of lack of combustion air available..
You'll get the 'feel' for it..