The T handle button operates a flat key that slides into a notch for each gear position. The very corner of the notch and the key gets burrs after years. I cleaned mine up a touch with a very small file and greased the trouble spots with a dab of lithium grease. I used to have to slap the T handle forward once before most every start. I still slap it forward :laugh3: but it's not necessary now, just habit.
I've heard that bending the cable mount a touch also helps.
Pop the gear shift cover up and have a look, the next time it hangs a little before going all the way into the park notch. You can see where it hangs. Both my 87 and 88 did this.