I checked my draft several times and I get 0 - 0.1 don't seem to be + or -
Where are you checking the draft? Do you have a barometric damper installed? Where is the coal you are burning from?
Most stokers leave what looks like unburnt coal in the ash pan. It could be 'bone", looks like coal but isn't. Does it snap in half easily? If not it probably isn't coal. Collect some of it and put it back on the fire,in the hottest place. If it doesn't burn it isn't coal.