Our 8030 has all of the above issues on all axis and the thrust bearing on the Y axis literally fell apart while running late last year. Sounded like a car crash. The Z axis ballscrew needs replacement and the X axis isn't far behind. I'm hoping they fail soon so we can throw away this money pit.
Check the Y axis gibbs first. If the problem isn't there, inspect the thrust bearing. While you have the motor off you can also check that the rotor spins smoothly with no play. Also check the coupler. The older brass ones make lots of noise when they develop play.