I went off the way down and scooter ran well until he got rid of the gas and then didn’t jump at all. Then had to go home with the train incl. scooter and then checked the following: Sparkling carburetors Gasoline supply Cylinders On the piston I found very small grains of sand but no abrasion on the cylinder walls. No plan why it no longer concerns. But the noise in the video is new to me (which unfortunately I can’t upload so I took a picture of my scooter on the train).Maybe it’s the V-belt but I’m not sure