There are 2 Z axis fuses. One for the DC side of the bridge rectifier and one for the AC side. You should be pushing 8 amps through the Z axis DC fuse.
Put it in step and monitor the base voltage as it turns on and off for each transistor. Monitor the output of each transistor as you step the axis.
Make sure all transistors are good, bridge rectifier is good, and no screws or washers on or in the terminal strip with the motor wires.
Do you have the screw in fuse holders? Or snap in?
Check the SMS board if so equipped and the resistor on the saturable core reactor.
T2 should be no less than 54 VAC and no more than 63 VAC.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)