General Directives for Assembly & Key Items
Install the crown the flat side inward.
Use flat head screws to fasten the motor to the inner chassis. Preferred screws are the NSR code 4856 m2x4mm (Engine locking screw smaller head).
Install the ball bearings/bushing pushing them gently in their receptacle. Once in place, install the axle and pull the two ends while firmly holding the Inner Chassis This will be enough for a good alignment.
One spacer 0.5-1.0 mm must be used between the crown and the bushing This will avoid collision between the crown and the motor screws. Take care of the axle's actual diameter. Although identified as 3/32 diameter axle, the actual size may be 2.37 mm (NSR) and 2.38 mm (Slot it and others).
The Inner Chassis is sized to host the Slot it oXigen chip.
Lightly sand the mating surfaces. Eg: inner to main chassis interfaces surfaces.
Use one Pick Up spacer to reduce friction. More spacers may be necessary for adjusting the chassis to ground clearance and/or compensating the potential mismatch (wooden Tracks) between the ground and the track power contact strips/braids planes.
Motor to model interiors clearance
After soldering the power cable to the motor, flatten the excess material as shown in the picture.