When chasing drivetrain noises, start by checking the hardware associated with the drivetrain.
A - rear wheel axle nuts
B - sliding drop out hardware
C - chainring bolts
D - crank bolts
E - pedals
The motor lock ring also should be checked. This will require a crank puller and a bottom bracket tool.
Remove crank bolt.
Remove crank arm using the crank puller.
Remove the lock ring to lubricate it. To keep the chainring from spinning pass a tool through the chainring and engage it in the rear most motor mounting bolt. The lockring is reverse threaded; turn clockwise to remove.
Add grease to the lock ring and install it again. Tighten it to 40 Nm.
