Place the 2mm pin into the shaft.
Insert the steel top gear.
Clip the e clip.
Slide the layshaft through the gearbox so that the slipper side comes out from the motor side.
Slide in the 5x10 bearing into the gearbox.
Place the idler pulley.
Place the outer gearbox cover and the other 5x10 bearing, then e clip the shaft.
Fix the motor Plate.
Place the first B4 slipper plate all the way in.
Place the spur gear with slipper pads glued thinly on the spur.
Fit the outer slipper pad.
fit the spring and the nut and tighthen. you will need to do adjustment at the track.
Your slipper is now ready but you need to modify your gear cover to protect the long end. So I will give you this tube which I will cut.
Basically you need to ream a hole at the center of the gear cover where the nut is, and then insert the tube. Make sure you don't ream too much, you need this to be a little tight fit. Place silicone sealant over the sides to seal the gear cover. Adjust the angle of the tube so that it is straight. Let the silicone glue dry overnight. After the silicone has dried, place superglue over the joint to stiffen it.
How the gear cover looks like from the inside.