Z axis won’t move on Geeetech Prusa I3 X
 

Hi,

When using Repetier-host to move the Z axis, I only get a noise but not any movement on the Z axis. The noise is like the motor is trying to turn but are not strong enough. (X and Y axis works fine)
When I try to turn the threading rods with my hand they are quite hard to turn. I don't know if the rods are bent, the linear bearings are bad or if I have done something wrong.
What I have tried to fix this:
I have eyeballed all the roods, and they look pretty straigh.
I have lubricated the rods with oil.
I have check that the threading rods are not stuck in the holes at the top.
I don't know what more I can do.
Can you help me to figure out what is wrong?

Any help will be apprecited.

I didn't find the right solution from the Internet.

References:
https://www.geeetech.com/forum/viewtopic.php?t=16917
Infographic animation company

Thank you.