I'm rebuilding the electronics of my Rapman 3.1 as well and identified the stepper motors as these: M57STH51-3008DC (Nema 23, X Y Z) https://www.motioncontrolproducts.co.uk/products/2/5/nema-23-57mm-high-torque-stepper-motors/ https://www.motioncontrolproducts.co.uk/productimages/cms/M57STH51-3008DC-S(rev.C).pdf M42STH47-1684SG (Nema 17, extruder): https://www.motioncontrolproducts.co.uk/producby VLPhoenix - Stepper Motors, Servo Motors, DC Motors