Thanks to the helpful information in various threads, I was able to diagnose the no-start problem on my 1650. Before consulting the forum however, I first bought a new ignition switch. The new switch didn't fix the problem, so I was about to order a solenoid, and then I thought that maybe the forum could help...
It was corrosion in the positive cable inside the eyelet at the terminal. A little baking soda and water did the trick. Thank you!