SOURCE checked the window lift motor resistances. It turned out to be 3.5 Ohms everywhere; up to 1.5 Ohms in some places. There must be a reason since the motors are identical. I disassembled and cleaned the sliding contacts and brushes themselves. Now all motors have exactly 1.2 Ohms. The cause was soot on the rotor contacts.

I don't understand what these contacts, which presumably should determine the driver's window position, are for, as they are not connected to anything in my car.

Для чего эти контакты, которые вероятно должны определять положение стекла водителя я не понял, так как они не подключены никуда в моей машине.