* Worn Clutch: This is the most likely culprit. A worn clutch disc, pressure plate, or throw-out bearing can cause difficulty engaging gears, especially reverse (which requires more force) and first (which is often the most heavily used gear). The smooth shifting once moving suggests the clutch is engaging *somewhat*, but not fully.
* Transmission Linkage Adjustment: The linkage that connects the shifter to the transmission could be misadjusted. Improper adjustment can lead to imprecise gear selection and difficulty engaging certain gears.
* Transmission Fluid: Low or dirty transmission fluid can cause shifting problems. Check the fluid level and condition. If it's low, add the correct type; if it's dirty, a fluid change is recommended.
* Worn Transmission Synchronizers: While less likely given the symptom of smooth shifting *after* the initial engagement, worn synchronizers in first gear could contribute to difficulty getting into first. Synchronizers help match the speed of the gears for smoother engagement.
* Clutch Master or Slave Cylinder: Issues with these hydraulic components can result in incomplete clutch disengagement, making gear selection difficult. Look for leaks or signs of failure.
Troubleshooting Steps:
1. Check the Transmission Fluid: This is the easiest and cheapest thing to check first. Ensure the fluid is at the correct level and is clean and the correct type.
2. Inspect the Clutch: Have a mechanic or experienced person assess the clutch's condition. They can usually tell by checking the pedal feel and engagement point. A worn clutch will likely require replacement.
3. Adjust the Linkage: This requires some mechanical knowledge and might involve removing parts to access adjustment points. Consult a repair manual for your specific vehicle.
4. Listen for Noises: Listen carefully for any unusual noises coming from the transmission, particularly grinding or whining sounds. This can help pinpoint the source of the problem.
Recommendation:
Given the symptoms, a worn clutch is the most probable cause. It's recommended to have a qualified mechanic inspect the clutch and transmission. Ignoring the problem could lead to more significant and costly damage to the transmission. Attempting to adjust linkage or other transmission-related components without proper knowledge could worsen the problem.
