Hi and thanks in advance for your help

I have recently baught a second hand cnc lathe cx1200y and I have found the machine has been running at 600mm/min. The manufactures sec said it will run upto 5500mm/min. I have tried running the machine at 1500mm/m at which the y motor (rotary axis) and the z axis seem to stall. I think it might be a motor issue because they are fairly big nema 34 motors but I can stall the y axis by hand. I wanted to know if there are any tests I can do with a multimeter to determine this.

iam confused because iam able to jog the axis at 5500mm/m still low torque but the motor will do it but if I command the machine to move to 0,0,0 point the motors stall. At anything above 1100mm/m the motor is stalling while the control software continues to think it's moving. Plus incremental jogging at anything over 1100mm/m the motor stalls or misses steps. There is very limited parameters I can change in nc studio control software but could it be anything to do with the setting of the acceleration setting? As it seems ok to jog fast but incrementally it stall/skips steps