I finally got my X3's head back on today and plugged 'er in. I followed Grizzly's instructions to break in the spindle and initially found the gear noise to be quite noticeable. But after letting it run lo-med-hi for 10 minutes each speed in the low and high range settings, it quieted down alot.
Even at high warp. you can feel it hum, but the base is pretty dead. Put your hand on the machine head, and you'll feel it. The motor makes some noise, but it's OK.
The most annoying part to an otherwise serviceable mill is the damnable emergency stop switch. If you look at the circuit diagram, the fwd/rev switch is included in the emergency stop switch circuit. These inscrutable orientals...
It took me a bit to figure out a dependable way to restart the system after merely turning the power switch off.
Make sure emergency switch is out. Set Fwd/Rev to center, power off. Now power on, set direction to Fwd or Rev, mill should start.
This is an overly elaborate way to de-energize the power in case of someone hitting the emergency stop button. I suppose that it's desirous to force the operator to power off and set the direction to off, but it won't let you just turn the mill on.