There are several tell-tale signs, but it all depends on your type of transmission.
Lincoln Manual Transmissions
The clutch system, which disengages the engine from the drivetrain to change gears, usually has the highest number of issues. Sometimes it just needs an adjustment, other times it needs to be replaced. If your clutch isn’t the problem, it’s your gearbox. Common warning signs are:
- Difficulty switching gears
- Unable to switch gears
- Grinding or a crunching sound
- Clutch slips or doesn’t “feel right”
- Burning smell or high engine revs
Lincoln Automatic Transmissions
Automatic transmission issues are far more complex than manual transmission problems because they have twice as many parts. In general, automatic transmission problems fall into four categories:
- Car is slow to move after putting gearshift lever in Drive or other forward gear
- Car doesn’t move when you shift into a forward gear
- Bucking and kicking when driving
- Slowing down despite pressing harder on the gas pedal
For more details, see the Kelley Blue Book article Do I Need a New Transmission?