X and Y operate correctly. Z is the issue. Connections look to be good. threaded shaft is lubricated, pulleys adjusted. Any ideas?
[IF you are using Easel, then re-do the machine setup and you will encounter a page where it asks you to verify the motion directions are correct and allows you to answer yes or no OR skip. most people skip this step, but IF you answer that your Z is moving inverted than Easel will automatically fix the setting that controls this.
OR you can manually fix it by reading your machines $3 setting, plotting that on this chart, then selecting the new value and entering that into the grbl settings. ( I suggest the prior method as it’s much simpler )
(More information here]