Were the motors exactly the same part number? I'm assuming not, but why change?
Was the encoder changed along with the motor?
Is the Haas engineer an actual Haas employee, or someone who says he knows the Haas machines.
The motor stalled out and was smoking, without an power interruption? Was all of the wiring checked out to make sure nothing had melted or shorted?
Was the driver/amplifier check out/swapped?
Th smallest/weakest wires in the harness are the encoder wires and that could cause a bad encoder symptom, so were they checked for damage/shorting?
If you want help, you need to give us more information.
Good Luck---Mike
Two Haas VF-2's, Haas HA5C, Haas HRT-9, Hardinge CHNC 1, Bother HS-300 Wire EDM, BobCAD V23, BobCAD V28