My 1995 J30 has recently stopped working in reverse. When the car is shifted into the reverse gear, the engine runs, but the car will not engage the gear, and not move. All other gears work fine. I've been told this could be a simple problem, such as a band or clip in the automatic shifter box. Can you help me locate this box and identify if I need to look for a clip or a broken band? Any other suggestions would be helpful.