The key is stuck, the engine will not crank over?

I have replaced the alternator, the starter and the battery. The key is stuck, the car will not go into park. When jumped it tries to start but doesn't start all the time with a jump. I have to try and adjust the slack in the in the shift cable and it seemed to have helped with the play in the shifter. but it still will not crank over. The release on the right side of the assembly that is actuated by the brake seems to have play in it and the shifter pin goes behind the assembly.