how do i know when the nuetral switch is going bad?

I read your question...and I'm thinking to myself "Don't you have to have ANY car/truck in Park before you start it?" ...Having it in Drive and starting it isn't a good idea. Are you saying it WON'T start in Neutral??

Your switch is bad. Fix it.

I've had them die the other way too, where the switch is ineffective and you can start it in gear. Makes it a little tougher on the starter motor, but should be able to pull it 'round. I think "safety" is the reason. Don't want it to start up and race towards you mechanic, who's standing in front of the car. When we were poor, we'd just short out the wires and ignore--life goes on--

its slop in the lever,floppy lever clearence,adjust the switch to compensate