Z-Axis motors vibration instead of turning! Please help ASAP

[SoupersSB]

So I have just assembled my first 3D printer, the prusa I3 pro B. When I click on auto home, The X-axis goes to its home position, the Y-axis goes to its home position, but then theres a grinding sound and the Z-axis doesn't move at all and the motors just vibrate unless I manually twist it to make it turn short distances. Please help me ASAP

[Gingko]

Hi,
1, You can check the voltage of A4988 of Z-axis first, adjust it to 1.0 or 1.1V.
2, Check these posts, there are much of information can refer to:
viewtopic.php?f=17&t=17038
http://geeetech.com/forum/viewtopic.php?f=82&t=60931

[SoupersSB]

Hi,
1, You can check the voltage of A4988 of Z-axis first, adjust it to 1.0 or 1.1V.
2, Check these posts, there are much of information can refer to:
viewtopic.php?f=17&t=17038
http://geeetech.com/forum/viewtopic.php?f=82&t=60931

Sorry, how can I check and change the voltage?

[SoupersSB]

Hi,
1, You can check the voltage of A4988 of Z-axis first, adjust it to 1.0 or 1.1V.
2, Check these posts, there are much of information can refer to:
viewtopic.php?f=17&t=17038
http://geeetech.com/forum/viewtopic.php?f=82&t=60931

Hey, I have found the issue, the 2 z-motors keep desyncing causing one to be lower than the other, locking them both up. Any idea on how to solve this desyncing?

[Gingko]

Check if the two side of Z-axis assembled correctly,
then adjust the hight:
viewtopic.php?f=22&t=16917%28thanks
https://www.youtube.com/watch?v=T9vI6DqAcmo&t=335s