A simple static check is to tape a straight light balsa stick to each el. half at the same place on each one, pointing straight back, beyond the back of the rudder, and then balance a third stick on the two taped ones, at right angles to them, and about the same width as the stab.

Then you can sight from the front, and check alignment ,at neutral, and during movement from neutral to full deflection.
(invert the model to check down elevator).