You should have 3/4"-1" or so of ash on the end of the burn plate when really burning. That is about good for any stoker stove. If you are pushing hot coals off the end, The adjustment should be backed out 1/2 turn (counter-clockwise) at a time on the adjustment settings.
If you have a black box control system, you may have to reduce the MAX feed down a few numbers. Only do a small change at a time and wait at least an hour to see what has changed.
Don't rush it. Coal takes time to adjust.
Every house/heating is different, what works for one person, may/may not work for another. Every setup is a bit different.
A lot of fine tuning and experimenting sometimes helps (and reading alot on here too!).
Don't worry about the flames, many stoves it will hit the top of it when really cranking.
What type of chimney or Direct Vent (DV) option do you have? do you have a Baro Damper? etc....maybe some details of your setup.