Gravely model "L" walk behing tractor.

I have a really old Gravely. Have used it over the years only occasionally. I recently reset the magneto points, set the valves, etc. It started and ran a while. I stopped to put more gas in and it will not start. I wonder if anyone can tell me exactly how to test the condenser. I have followed some instructions from another web site using an ohm meter. The condenser tests "open". I understand the meter should jump up and slowly fall back. Any help?