Problem starting a 1997 Toyota Camry

I posted this back on March 31:
My girlfriend has a 1997 Toyota Camry with a 6 cyl engine. Low mileage - only 66k miles. She has a very sporadic problem for about the past year. Yesterday it happened for the first time in two months. She tries to start the car and gets a click. She turns the key back and it starts the next time she turns the key. Yesterday, it failed to start twice before it turned over.

The problem became worse about six weeks ago. I replaced the starter on September 27. On October 7, the car again would not start. No click this time. About 4 hours later it started no problem. On October 8, I replaced the starter relay. Last night, October 19, car would not start. Completely dead - no lights, radio, etc. New battery - installed in August. It would not start this morning. Battery measured 12.37 volts. I am charging the battery right now and will try it again later.

Any ideas what is going on?

If the battery measured 12.37, it is fine, or good enough that the lights should come on. I’d suspect the ignition switch.

Have you tried putting the shifter in neutral, brake on, and trying to start it? It could be the interlock switch.

texases - I did try that. I don’t think this car has an interlock. Too old. It does have a neutral safety switch. I put it in drive with my foot on the brake. The key will not even turn so the NSS appears to be functioning.

Pretty sure it’s not too old, my '96 had one.

If you test the interlock switch at @texases suggests and it is something else, check both ends of the battery cables for corrosion.