Your English is certainly adequate. when you can put your hands on the machine, without electricity to the motor, try turning the chuck by hand. Rotate it forward and back. If it won't turn at all, move the lever in question to another position. It's possible lit may not move easily. If it does move, attempt to find out if it will slip into and out of it's current position, and an alternate position. When is in an alternate position,, attempt to turn the chuck. It may be free, it may be stiff but able to be turned. . These are the three possibilities. 1) won't turn at all, 2) is free to turn and, 3) will turn but is engaged in gearing.
The first, Won't turn, means that the gear train to the motor is such that the motor will turn it slowly. The Second, Is Free, means that it is in "neutral" and another lever must be engaged to connect the gears. The third means that it is in "high" gear and the motor will spin it quickly.
I hope you can understand my explanations.