Take Up Motor System

Got a chance to do some torque measurements. The results matched up with some calculations I got from one of you. Here are the results (also see question at bottom, please):

Conditions
Full reel on take-up side, film fully threaded through film path, ~1m wrapped around core of feed side. This is the strongest dead-stop load possible on the system.

Test setup
Spring balance, arm lever. Balances were tested with weights for accuracy. Margin of error: +/- 0.2N

Results
with NO MOTOR attached to shaft: 3.74 kg/cm average reading
with motor attached to shaft: 4.36 kg/cm average reading*

Question
I’m new to this scientific measurement stuff. For accurate reading, should the motor be attached or not?

*NEMA 23 Stepper, type 57BYGH405A