Where is the damage if the second gear of a manual transmission cannot be engaged?

[Herb]

If the second gear of a manual transmission cannot be engaged, it may be due to unclear clutch disc separation, or damage to the clutch disc and clutch pressure plate. Notes: When downshifting, the method of two-clutch operation plus one blip of the throttle should be used. The principle of downshifting with a throttle blip is: the faster the speed, the larger the "throttle blip"; the slower the speed, the smaller the "throttle blip"; the lower the engine speed, the larger the "throttle blip"; the higher the engine speed, the smaller the "throttle blip"; on flat roads, the "throttle blip" is larger, while uphill, it is smaller. Gear shifting techniques: Shifts should be timely, correct, smooth, and quick. When starting the car, generally use the low gear (first gear). After starting, as long as road conditions permit, quickly and timely shift up to higher gears.