Nema17 torque after dissasembly

Motor PN: MS17HD4420

4 = 34.3mm length

weight = 225g (slightly higher than MS17HD4P4100)

Torque should be about 0.33Nm.

"420" is the winding current rating but its not clear what this would be, somewhere between 1.0 and 1.5A. Probably closer to 1A.

Internal construction of stepper motor (source):

Known as "hybrid stepper motor".

Front and rear rotor cup sandwich a permanent magnet, which should hold the magnetic field in the laminations. Perhaps older stepper motors did not have this magnet and were more susceptible to field loss.