When you say, the nut was loose that holds the switch...what exactly are you talking about. If it by chance is the solenoid, like Inline said, not only could the internals be bad, but if you tighted then nut that holds the wire down you could have spun the stud internally. They have a jam nut that hold the stud in place, if you tighten them and happen to spin the stud in the jam nut, you may get it tight but damage the internals in the process. I say this because you said it started fine after you tightend it, but then it didn't later.
Are you comfortable jumping across the solenoid to rule it out? If you are getting a click and all else checks out, I'm leaning to the solenoid.
"But if serving the Lord seems undesirable to you, then choose for yourselves this day whom you will serve, whether the gods your ancestors served beyond the Euphrates, or the gods of the Amorites, in whose land you are living. But as for me and my household, we will serve the Lord.” Joshua 25:15