Z-Axis Center Help

I have found that when assembling my Anet A8, the Z-spindles are very tightly guided in the upper bracket.
Even after correct adjustment of the spindle clutch to the motor, the spindle stuck just 3mm in the upper hole.
That was not enough for me and the spindle wobbled while printing in the hole back and forth.
With my centering aid, the spindle remains very quiet when printing.