First apply double-sided adhesive tape, then tape such as those used on the Tennis and badminton racket to get a firm grip with your hand.

 

Such tape has high friction and it is important on the capstan wheel. If you need to change the tape, it will be easy as it is adhesive tape.

Put a screw from the bottom on the Capstan-guiding-base M3X30mm and M3 nut on the top. The screw should spin easily, use a 3mm drill bit if necessary.

 

Screw-protection-nut use M3 screw and thread this, all the way in. Before assembly.

 

Distance to stepper motor seen from below, should sit on top of stepper motor so it has a flat surface and the shaft is lowered.