On one side reattach the plastic block to the MGN block. Slide in both retaining wires and screw in the rubber end cap.

Add a drop of Super Lube into the holes where the ball bearings drop in(this will help prevent them from falling out. Start inserting ball bearings into the hole channel. When they fill up place the second plastic block into the MGN block and attach the retaining clip.

Insert the remaining ball bearings into the inner channel. There should be a small gap in between the ball bearings.