shift out of park

I have a 97 GP GT that will not shift out of park unless I push the shift lock button. And it's not intermittent. I don't have any problem with my keys not coming out though. For the past 6 months, I've had a wire tie wrapped around the shift lock under the console to make it work. But now I'm trying to sell the car and I want to fix it right. Here's what I've done:

1. I just replaced the shifter assembly, hoping it was the solenoid. I also made sure I was getting juice out of the plug that goes to the solenoid and I cleaned the contacts. That didn't work.
2. I also took off the two white plastic switches that are screwed in under the steering column where the brake pedal shaft rests on the switches and then releases when you push the brake down. I took those apart and cleaned the contacts. (I have no idea if those switches have anything to do with the shift mechanism). But in either case, that didn't work either.
3. I checked all fuses, especially the BTSI and made sure the fuse was connecting with the box.

I have no idea what to do next. Is there another switch or something that might not be working?? I'd appreciate any suggestions.

O.k. nevermind. The new shifter assembly with the solenoid does work! When I plugged the electrical wires back into the solenoid, a wire came loose and I didn't see it. I'm glad that's all over with. Works great now!