Check up/downthrust in a level/trimmed powered flyby. Cut throttle. Obeserve up or down pitch. Ideally it should continue level for a ways.
Back to full power. It should not pitch up or down, but continue a level flightpath. Adjust engine thrust to achieve a neutral behaviour.

Side thrust is checked with a level powered flyby, then smoothly pull into a vertical. If you need execessive rudder to draw a vertical line, adjust thrust line L or R

Your flying surfaces must meet required incidences per manual before the above is tested with success.