The manual shifter will lock in sixth gear?

If the clutch is not working correctly, it will cause this problem, do you have issues with any other gears? If not, it could be the shifter can wear out or needs to be lubricated. Here is a video to help see the condition of the clutch and I have included how to service the shifter in the images below. Also, check to see if the clutch fluid is down. I have included the clutch master location and replacement instructions in case it is leaking.

https://youtu.be/EpBMj5ZY_bo

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.

Thanks for trying to help but my clutch does not slip, it doesn't go to the floor and the (2) best transmission shops in the area drove it without incident and determined that it shifted and worked fine but then after I get it back it will lock into 6th gear only whenever it feels like it. Sometimes when I shift from 1st to 2nd it will go into 4th. I did all of the clutch tests prior to u sending me the video and didn't have any of the issues in the video. I have a Mercedes transmission and engine. You have to drop the transmission to get to the hydraulic clutch.

Yes, the shifting mechanism is where I would start, it could be just an adjustment for the cables, I would take it apart to look to make sure it is lubricated and adjusted correctly, you may have a shift cable that has worn slightly. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.

Thanks for the advice. I am due for an oil change in about (2) months so I will have them check the shifter cables then. Until then I will continue driving the vehicle without using 6th gear. It tachs out at 6,000 RPMs so even at 80 MPH in 5th on the highway I'm at 2-3K RPMs, it just uses a little more gas than when I'm in 6th.

Binding shift linkage or a binding shift lever can result in difficulty or no shifting. The same is true for the shift rails located inside of a transmission. These shift rails have detent springs/pins that can stick, leaving a vehicle unable to shift.

Additional info: (2) years ago I had my manual trans serviced. They noted on the invoice that there was a spring and ball bearing laying in the drain pan but they didn't know where the parts went. So, they drove the car and also noted in writing that there were no shifting issues but if I experience any problems they recommend trans replacement. That was two years and I have been driving the vehicle ever since with no issues until now, the shifter will intermittently stick in 6th gear.

The problem can be definitely internal, I like to rule out the easier stuff first.

When a repair shop says, I'd just replace the transmission, I like to do a process of elimination first by looking at the easier stuff first and then move on to the next items.

Yep, good call. Please upload images of any parts that have failed to help anybody else that has the same problem. Let me know what happens.

Will do.