The axle washers must be fitted on either side of the frame dropouts to prevent the axle from damaging the frame as shown below:
The only physical connection between the axle and the rotating wheel is the two wheel bearings, and I have not yet come across a seized bearing on a new motor.
If your rolling resistance is greater when pushing the trike backwards, it could be that the freewheel's gear cluster is binding against the frame because the innermost axle spacer washers have not been fitted.
The freewheel should rotate easily when you pedal backwards with the wheel stationary, if the freewheel is jammed against the frame, then it will probably refuse to move when pedalling backwards, forcing the chain to pull against the spring loaded derailleur mechanism making the chain sag along the top run between the freewheel and the chainwheel.
However, if the binding is
not due to the freewheel touching the frame, then it could be due to an alignment problem with the rear brake mechanism.
The only drag that should exist is the magnetic forces acting between the rotating motor ring and the fixed stator on the axle, therefore the wheel should rotate relatively easily when pushing with just one finger against the outer diameter of the tyre with the wheel raised off the ground.
If the freewheel or the brakes are binding badly, it might account for your unusually low range
(8 miles) with a fully charged battery on level roads.
Alan
