Firstly, disconnect the machine from its power source

Disassembly procedure:

Toole needed:

 M3/M4/M5 Allen Wrench

Tips: Loosen in anticlockwise, tighten in clockwise.

1. Loosen two upper screws on the buckle then take out the belt;

2. Unscrew and remove four screws from the blue base;

3. Unfix two screws on coupling

After that, please remove this drive shaft, like below.

Reassembly procedure:

Tips: put four screws and the belt into the blue base firstly, like below.

1. Insert the shaft into coupling then fix the blue base with four screws; 

2. Slide the coupling to proper position as the right sides shown, then fix it.

3. fix the belt, like below.

This video is for reference:

End.