Install M3 x 25 SHCS, M3 Washer and M3 Nut into the Idler assembly. Only put the screw in until the tip is flush with the nut.
Tip: Set M3 Nut into hexagon cutout and hold the nut with your finger to install the bolt.
Spin the bearing inside the idler to make sure it rotates smoothly.
Install 2x M8 washers onto hobbed bolt then a 608 bearing.
Once installed, does the hobbing on the bolt line up with the small hole going through the extruder body?
If you need to adjust it's location, you can add either a 0.50mm or 1.0mm shim washer to get the correct spacing.
Shims only needed if hobbed bolt doesn't align with hole.
Note that 2 .5mm washers equal 1 1.0mm washer and 2 1.0mm washers equal one M8 washer. So you shouldn't have more than 1 .5mm washers or 1 1.0mm washers.
On the opposite side of the gear, add a 608 bearing, M8 Washer and a M8 nyloc nut.
Tighten the nut down until the bearing is seated and there is no space between the Nut, Washer and Bearing.
Check the hobb alignment making sure the center of the hobb is lined up with the center of the small hole going through the extruder body. You may need to go back and add or subtract a 1mm shim washer or .5mm shim washer.
The large gear shouldn't be able to rock back and fourth, but should spin freely.
Rotate the large gear several times making sure that the assembly and bearings rotate smoothly.
Locate the flat side of the motor shaft.
With the set screw aligned with the flat, slide the small gear onto the motor shaft.
The location will be adjusted later so positioning isn't important at this point.
Tighten the screw just enough so it doesn't turn off the flat, but loose enough so it can slide up and down.
Install 2x M4 nuts into the bottom recesses as shown.
Holding the motor in the location where it will be mounted, align the herringbone gears by sliding the small gear in or out on the motor shaft so the V-grooves are centered on each other.
Install motor using 3x M3x12 SHCS and 3x M3 washers, taking note of the orientation of the motor wires.
Push the motor down with slight pressure while you tighten the bolts to make sure the contact is tight.
Tighten the set screw on the small herring bone gear.
There shouldn't be any backlash in the gears.
Install 2x M4 nuts into the top of the extruder body as shown.
Make sure you can see the nuts from the side so you can install bolts later.
Tip: Nuts only go in one way, the flats of the nut must be vertical.
Install M4x55 thumb screw, M4 washer, extruder spring, M4 washer and Extruder latch into M4 nut installed in body.
Then put another M4 x 55 with thumb knob, M4 washer, extruder spring, M4 washer through the Extruder latch and into the body.
Make sure extruder latch is oriented correctly.