Woooooah !!! I would definately never start up my scooter like that with the cvt cover off
The starter bendix has nothing to hold it in place, ie the other side of the cvt cover, the bendix can rattle around and hit your outer variator givng you big trouble. If you need to run it with the cover off i would advise removing the bendix, putting the cover back on and kick starting it. Then carefully remove the cvt cover with the motor running. Only do this if you really have to tho, not just for fun.
I doubt your bendix is the problem anyway, if you look on the other half of the cvt cover you will see a small hole? That hole is where the end of the bendix goes into, that keeps it secure and stops it rattling.
You really need to get an impact wrench and get the variator off asap. Trust me you wil use the impact wrench again, to service rollers, clean clutch, change belts, etc, etc so its a good investment. Besides you dont want to break any more tools, or even your transmission trying other methods. Also make sure you ut some threadlock on the threads before you refit you variator nut or clutch housing nut if you remove them.
My guess is either your rollers are worn right down to the brass and it them rattling,OR, your variator ramp plate is loose on the boss and is rattling,OR, the plastic guides on the variator ramp plate have worn, come loose or broken. Either way, until you get the variator off and have a look, it could be any of these things, or something else.
Let us know what you find once you get in there