Shifter issues
the transmission itself doesn't have any thing that would lock in gear. There is the Detents which help to place the shifter shaft in the correct posistion for the Valve Body.
BC
IIFC, You would normally press the top button and release to shift out of Park into reverse. It should then click as you shift from reverse to Neutral and then OD, 3, 2, 1.. if you don't feel the detent/click or momentarily stop. I would look at the shifter.
You should also have to push the button to shift from neutral to Reverse/Park.
If you go under the car, disconnect the shifter at the trans, you should be able to move the shaft and feel if the transmission internal detents are working, it should click at each shift position. but you should be able to just completelyh shift right through all of the gears without anything to stop you (that is the shifters job).
You could go either way, new/replacement or aftermarket. you call ...
BC





