Hello Dave,
as I can remember we had several cars we had to take off the engine because of clutch problems.
The problem has been, that they forgot to grease the transmission input shaft the friction plate moves on.
But this mainly did cause a problem to engage gears.
When you check the car and you test if the car wants to roll slightely when you move the gearlever in direction of the first gear -
but first gear not in - this could be the problem...maybe.
This would mean the friction plate always causes a turning input shaft, even when the clutch pedal is fully down, maybe this causes
that you can`t get the gear out? Just an idea....

Regards
Frank Morgan Park Hamburg