G213V possibly smoked a mosfet on first attempt

Trying to wire up Gecko's nema-23 5A motors with G213V gecko drivers using 10micro step and run on Mach3, motors driven from a DC 28V 18A Antek power supply. The power setup that came on the machine origionaly worked fine but just didnt have enough motor resolution for what i want so i tossed all the electronics and motors but kept the Mach3 PC to use. So i know the PC and mach3 work fine. Motor setting need tweaked again certainly.

So heres the problem. If i connect the "common" terminal on the Gecko drive to the common tab on my 28V motor power supply the motors have holding torque but will not move when commanded from Mach3. So i tried connecting one drives common terminal to the power supplys - tab. Then the motor ran perfect for about 5 seconds before i noticed the smell of burnt mosfets and the motor stopped. The green light still comes on from the drive but the motor will no longer move. Im stumped. I think i have something wired up wrong obviously but im not sure where to go from here.

Heres how i have the drives are wired up.

110V AC goes into the 28V DC power supply for the motors. The motor drivers power connections are connected to the + / - tabs on the DC supply as normal. The DIR and STEP pins are connected to each drive from the PC parallel port and also there is a parallel pin connected to each drivers DISABLE terminal that gets 6v when Mach3 goes into E-stop mode. This E-stop pin would not output voltage until i connected one of the parallel ports ground pins to the DC motor power supplys - terminal. There really is no true earth ground connection for either the PC or the DC motor power supply. The common terminal on the DC motor supply is not connected to anything.

I also tried using a second driver and motor. I connected the PC parallel ports ground pin to the DC motor supplys common terminal and with the drives common terminal connected here as well the motor ran for a few seconds and then stopped and would not run anymore. But no burnt smell or anything wierd with that driver, just wouldnt go anymore.

We can replace the burnt mosfetts but i dont know where to go from here. Gecko's tech support is off for the day aparently and their driver instructions are vague to say the least.