Yes, Your Car Does Need Transmission Repair!
If your car is having problems during shifting, this doesn't necessarily mean that the transmission is in need of repair; for example, if you cannot get the car out of park, this may be the fault of a cable that connects the brake pedal to the shifter. This cable won't allow you to shift out of park unless the car senses your foot on the brake; if this cable is broken, the car will be stuck, even though the transmission itself is fine. While some problems with shifting are that simple, others may be more complicated, and may signal that certain gears and other pieces need repair or replacement. Note a few signs that typically indicate that yes, your car does need transmission repair.
Slipping out of gear
Your car should never slip out of gear unless you actually move the lever. There are many safety mechanisms that keep the shifter and the gears of the transmission in place while driving, and there is no reason for them to fail unless they need outright replacement. This problem will tend to get worse over time, causing your car to stay in neutral no matter the gear you choose.
Buzzing or grinding
When you put your car into a new gear, the parts of the transmission shift and then rotate chains and gears, but these parts should all move smoothly and easily. If you hear a buzzing or grinding sound when you change gears, this often indicates that there is metal-on-metal contact or that those pieces are not meshing together properly. This sound can soon turn to clunking as the pieces try to move together without being properly aligned. Adjusting the chains or replacing the gears should get the transmission working again properly.
Burning smell when you change gears
Any burning smell should be investigated, as this can mean that the engine is running too hot and burning oil or that leaking oil is dripping on a hot manifold. If you notice this smell when you change gears, then usually the transmission is the culprit. Gears could be grinding together, and the metal is burning from this abrasion, or there may not be enough transmission fluid in the reservoir tank to keep the gears running smoothly. The transmission fluid itself may also be old and corroded, and it will then have a burnt smell. You will notice this smell more when the car changes gears, and it's good to get this diagnosed and fixed before serious damage is done to those gears.