The stepper motors are all (externally) unmarked. As such, gathering information for them is quite dificult. It is known that they are type NEMA 17, 2-phase hybrid bipolar. They are fairly easy to replace, however, as long as you know the specs you are looking to match.
NEMA17 - 40mm
170mm x 170mm x 400mm depth
NEMA17 - 34mm
170mm x 170mm x 340mm depth
Step Angle 1.8。
Step Angle Accuracy ±5% (full step, no load)
Resistance Accuracy ±10%
Inductance Accuracy ±20%
Temperature Rise 80。C Max.(rated current,2 phase on)
Ambient Temperature -20。C~+50。C
Insulation Resistance 100MΩMin. ,500VDC
Dielectric Strength 500VAC for one minute
Shaft Radial Play 0.02Max. (450 g-load)
Shaft Axial Play 0.08Max. (450 g-load)
Max. radial force 28N (20mm from the flange)
Max. axial force 10N