Kymco Agility City125 Variator and Clutch *****

Kymco Agility City125 Variator and Clutch
cam: Galaxy S2

[Sidg]

I have new TVS Jupiter and it is just 4.5 months old and just 2550kms total run. 2nd free service is done. Tyre pressure is ok. Engine oil and gear oil is just changed few days ago. Rear tyre is freely move.
My problem is that the scooter is always start to vibrating around 45 to 50 km/h speed and if two persons are sitting on scooter then its vibration increases and start from 35 to 50km/h speed. After 52 km/h speed no more vibrations. Vibrations coming from handle, floor board and slightly from rear side when pillion also sit. Is it required to use sandpaper in clutch cover, clutch shoe, rear tyre assembly and rear brake shoes and also clean the clutch cover and greasing the rollers in clutch and variator? I see some videos on internet to use ragemaar/sandpaper in rear tyre's internal assembly area, brake shoes, clutch shoes and also clean the clutch area and greasing all rollers of clutch and variator but it is not mentioned in TVS manual book and also service centre guys had never done it.
I told this vibrating problem to TVS service centre during free service but they just tight the all screws.
What you think, what is the actual problem of vibration around 40 to 50 km/h speed. Is this a problem of clutch shoe, Variator, rollers or something else? What is the solution? Please help me.