The original shifter interlock is made from plastic. At some point in time as it ages, the little hook of plastic that holds a spring, breaks and releases the spring and no shift ! The attached pic is the piece out of my car ! I was lucky it happened for me, while parked in my garage at home . . . did a google search, and then off to NAPA for the Dorman replacement part - made of Anodized aluminum - no breaking in the future !!, and took about 1 hr to pull apart and replace !! . . . the "white spot" on the pink part is where the little hook broke off . . . and yes, that is the actual color of the part !!! Again, you can get the shifter working, without changing it, but it's a "jury rig" kind of thing . . . best to google the issue !!!