A couple of thoughts on how to approach it. Clean battery cables connections are one thing but the negative cable gets overlooked. Everyone tends (me too) to look at the positive cable. First check the negative cable connection on the engine. This should be clean and tight. If it's bad it will give intermittent starting problems. Fooled me real good one time.
Next you said you checked the 2 small terminals on the solenoid while cranking. I'm assuming you were measuring these to ground while someone was turning the key (clutch pedal in). Also assume when this was happening the solenoid did not "click". The terminal you care about is the inside one. The solenoid has a "S" embossed in it next to the terminal. This should have 12 volts on it while trying to start the car with the clutch pedal pushed in. If it doesn't the purple lead coming into the solenoid has no power. This lead comes from the clutch pedal switch. The other side of the clutch pedal switch is the wire from the ignition switch. This wire has power when the ignition switch is turned to the start position. Sounds like the problem is either the ground cable or the clutch switch. Take a few more readings and post back if you can't find it.
Next you said you checked the 2 small terminals on the solenoid while cranking. I'm assuming you were measuring these to ground while someone was turning the key (clutch pedal in). Also assume when this was happening the solenoid did not "click". The terminal you care about is the inside one. The solenoid has a "S" embossed in it next to the terminal. This should have 12 volts on it while trying to start the car with the clutch pedal pushed in. If it doesn't the purple lead coming into the solenoid has no power. This lead comes from the clutch pedal switch. The other side of the clutch pedal switch is the wire from the ignition switch. This wire has power when the ignition switch is turned to the start position. Sounds like the problem is either the ground cable or the clutch switch. Take a few more readings and post back if you can't find it.
