Thought I'd through my two cents in as well, (course I won't have any left but oh well.
) It looks like you need to add a whole lot more coal to that stove I burn the exact same model and I'm pretty much loading the coal up until it comes spilling over those 3 bars. Then I pick it up and gently toss it in the back corners until you can't see more than an inch of firebrick except right at the front.
I'm still learning the whole coal burning process but I also ran into a situation this year that I hadn't before. I managed to get an ash bridge at the back of the stove, darn thing would get much over 400 and I was shacking the #*%$#* out of it, those grates don't always break everything up so every now and then I go in from the top and poke straight down throughout the coal bed it made a world of difference, about 30 min later I was roasting at 600+
Other than that listen to these guys man they helped me out a bunch.
P>S> as a note of caution I was giving the stove a good cleaning, poking and prodding the 3 bars clean and pulled out that curved metal plate the runs below the three bars and is where the ash pan used to be on the older models. With the plate out I close the doors and commenced with the shaking and noticed that the u shaped bars that make up the grate, every-other one had fallen out of the holder in the back and I was in serious risk of dumping a fully loaded coal fire into the ash pan
I managed to realize what was happening and used a couple pieces of wood to "reach" in and lift those bars back into position, talk about sweating bullets. Moral of the story make sure that the curved metal plate is in place before shaking with vigor