the flame is about right on idle. MIne looks aobut the same.
Do you have a Thermostat or Coaltrol to control it?
Does it have a screw feed adjustment? how many turns OUT do you have it?
When you turn up the thermostat, does the stoker motor kick on steady?
It take quite a while for stokers to come up to temperature, maybe 30-60 mins, so you may not notice it right away, but it will eventually burn more towards the front of the grate when fully burning.