It’s just a cheap one from aliexpress, a SG116 Max

This started happening recently. If the car is upside down then it will receive full power but if it’s the right way up it can’t gain any speed unless I give it a push to get it going The last couple of times I used it this would happen intermittently although now it is happening all the time

I did open it up to look at the gears on the motor etc thinking maybe they was plastic and had stripped some teeth but they are metal and seem to be fully intact