Neutral Switch Problem

Hi my name is Phil and I just found this site. I know a lot about construction but very little about cars. I hope someone can give us a hand. My son has a '93 E-150 Van with a 5.0 liter automatic in it. His shifter has a lot of play in it and occasionally it would not start until he would push up on the shifter and then it would start. The other day it quit starting all together. Turn the key and you could hear it click once. Tried playing with the shifter but nothing. Replaced the solenoid and still nothing. We replaced the neutral switch tonight and it started right up. Started it several times. My son went out to move the van a little while ago and it won't start. It's doing the same thing, just clicks once and nothing. Played with the shifter and still nothing. Any help would be greatly appreciated.

I would tighten up the shift linkage and adjust the safety switch if needed.
Use an ohm meter and make sure its working properly when its in neutral or park.