BBS02B noise when pedalling

[weng]

Hi,

I heard this squeaky noise in my BBS02B when pedalling. This video was recorded without the battery attached or the motor running. It was dead silent when I got it but after 100 kilometers this happens.

What's the cause, do I need to grease the gears?
https://youtu.be/o5Pa-S-Y1WA

Thanks