Hi,
If the slave and clutch master cylinder are new and working, it has to be an internal clutch issue. Since you can shift it with the engine off but not running, the clutch isn't disengaging.
A worn or damaged clutch fork or pivot point can be an issue. The clutch fork and pivot can wear out or become damaged over time, preventing the clutch from disengaging.
Also, a damaged pressure place, or if the clutch disc is completely worn, can cause the issue. At this point, I feel the transmission needs to be removed and the components need to be inspected.
I attached the directions below for replacing the clutch and pressure plate (pics 1-9). After those directions are the directions for removing the transmission.
Let me know if this helps or if you have questions.
Take care,
joe
See pics below.
Images (Click to make bigger)
Tuesday, September 5th, 2023 AT 6:45 PM