[PNJSNAK]

I am having a bit of trouble with my tranny, when at cold operating conditions engagement of shifter into all gears when the clutch is engaged is fine. After tranny is at running temperature after 20 to 30 mins of easy driving, engaging 1st gear is very difficult. Almost feel as though I am forcing it into gear. Other gears no problem, even reverse. I believe I have the clutch manual cable adjusted properly. Even if I move the adjustment nut back and forth it is still hard to get into 1st. The tranny was rebuilt about 9k miles ago. It seems I have been having this problem for at least the last 4k miles or so.
Any help or suggestions would be helpful.
Jim