First Gear Not Fully Engaging
 

I have a '00 LS 5-speed and 1st gear has an issue where it won't fully seat in the gear without holding it there. I move it into first and then the gear knob will "spring" back about 3/4". This happens whether the car is on or off.

9/10 times its ok and it grabs first fine, but sometimes it won't fully grab the gear and I'm greeted with a huge jolt as I let out the clutch (almost feels like being rear-ended).

If I hold it all the way in gear (gently) it will take off fine every time.

I just changed the shifter boots, bushings, and turret oil, and it didn't really help the issue.

Any ideas?