I’d suggest checking the following, as they are the easiest to do (in order) and most likely culprits:
You may also want to check that the little screws in the pulleys are still tight and one is in the middle of the flat on the shaft. If they’re slightly loose, it’ll allow the shaft to turn before the pulley does, which can increase the slop.
By re-calibrating, do you mean that you measured and adjusted the steps/mm? That’s something that’s going to be unique to each machine, so to get maximum accuracy you should do that. There’s a video on how to do that calibration at Steps/mm Calibration
Finally, your belt tension and pots may be slightly off. It’s possible that a loose belt is allowing a little more slop. I don’t think it’s your pots, but that’s not outside the realm of possibility. There’s videos to check them both at X-Carve Maintenance/Troubleshooting Videos - Add Your Own!