Alaska Channing 3 not getting hot?!?

Hello all I'm noticing my Alaska Channing 3 stoker isn't getting hot until I dail Rheostat to 4-5 with last year having it dialed to 3 would heat you out of the house. I'm also using alot of coal to. I cleaned air grate, i replaced all gaskets and greased the feeding arms and also cleaned the direct vent system. Any ideas would be appreciated thank you.

Did you happen to come across a solution? I just fired up our Channing 3 yesterday (first time coal burner) and I too was a bit underwhelmed with the heat output. Seems like I went through half a bag of coal (40lb bag) in about 6 hours with rheostat set to '2'. Turned it to 1 overnight and it seemed like cold air coming out the blower. Is all our heat getting sucked up into the power vent?