Geeetech

I have a problem. The instructions are:

1.Thread a M3 hex nut to the M3 x 50 screw.
2.Thread the A21 to the M3 x 50 screw.
3.Thread the spring to the the M3 x 50 screw through the hole of A21.
4.Thread A22 to the M3 x 50 screw.
5.Thread another M3 hex nut to the M3 x 50 screw, compress the spring into the M3 hex hole on A21 and A22, you need to use some force.
6.Mount them on the Left bearing bottom plate (No.A18 ).
7.Fix it up with 2 M3 x 30mm screws and M3 hex nuts.
http://www.geeetech.com/wiki/index.php/ ... Prusa_I3_X

But, Step 2, Thread A21 -- this doesn't tighten or hold onto any part and just slips through.

A21 slides through and the M3x50 doesn't hold.

See video #1:
https://drive.google.com/file/d/0B1bQ2w ... sp=sharing

Notice that A21 is loose and falls right through!

Video #2
https://drive.google.com/file/d/0B1bQ2w ... sp=sharing
Assembled, the M3x50 doesn't adjust -- its loose and moves freely. It should not move, but the height should be adjustable.


Please help me assemble this part correctly

That's normal, you need to keep tighten the top M3 nut down to the surface of the A22, so the two nuts will compress the string into the A22 and then the bolt will be hold tight.
See the picture below: