Z-axis assembly step 7 problem(?)  

Z-axis assembly step 7 problem(?)

Step 7 has me placing the pre-assembled X-axis onto the z-axis lead screws. You then turn the lead screws by hand to somewhat level the x-axis. During this step I find the left-had z-axis lead screw is much harder to turn when compared to the right. 

There are two comments in the online manual where others have had the same problem. The solution was to loosen the two screws holding the trapezoidal nuts until the lead screw turn easily. 

I have done this but the screws need to be completely loose for the lead screw to turn easily (or at least the same as the right-hand one. Is it ok to leave them loose?

Things I've tried:

• re-clock the trapezoidal nut to use the other two holes
• lightly sand the top of the plastic part to remove any tiny bumps
• check the trapped nuts for centration in the screw hole

Am I just being paranoid? I think the z-axis motor is probably strong enough to overcome the drag. It just seems like a bad thing to have one motor dragging and the other not.

Suggestions?