welcome to the forum from a fellow S200 owner! How many miles on your scoot? Do you know the history of it? Any pics you can share with us? We love pics.
When refilling the rear gear oil use the amount stamped on the cvt cover..180 ml, I believe, and don't just fill until it runs out the fill hole. That's way too much and the extra will get vented into your airbox, ruining your air filter. Most of us use a large syringe to fill the correct amount of gear oil.
No real problem areas with this scoot. All my issues have been maintenance type issues on wear items that are easily fixed (cleaning pilot jet in carb, new rear brakes, sanded off the glaze on clutch pads and most recently, changing fork oil).
Might want to check/change the front brake fluid, that is one that gets neglected, and clean up and lube your front caliper. Valve clearance may need to be checked, depending on your mileage, air filter, plug, the usual things.
There's a sticky in the s200 forum showing the process for removing all the plastics and everything else to get the rear wheel off..it's a useful skill to have with this scoot.
Finally, where are you located? It helps people give you better answers to your question if we know the country you're in.