Stick the axle so it's in one bearing, put a little pressure on it, and turn it. Should be smooooooth. Repeat on other side. If not smooooooooooth

change them, but otherwise run it.
Most critical thing...4 nuts on the pumpkin need to be loose when you torque down the axle.I recently had a mechanic change my rear splines. Riding around the first day, I had some vibration in the mirrors that wasn't there before. I decided to retorque the 4 nuts, axel and rear brake stop bolt. It felt like everything had been tightened with a pneumatic wrench set to "Moose on steroids." Torqued it all back to specs, and in order, no more vibration.