Bought a 1952 Ford 8N with 12 volt from folks I bought my house from. Started and ran in Feb 2015 when I bought it. Tried to start it recently and it wouldn't turn over or even click. Charged battery still nothing. Friends helped me diagnose that solenoid was bad... Replaced that. Drained the old fuel and replaced with new as it had been a couple of months. Now with a new solenoid and fuel it turns over, catches great and runs as long as I want to hold in the ignition button. Once I let go of the ignition it dies within 2-3 seconds. Any helpful thoughts on what to try next? I am a newby owner with no mechanical background. Anything constructive is appreciated!!