1989 F250 Ignition problem

I have an '89 F250 302 standard transmission. In order to start the truck you need to push the clutch pedal to the floor. Well, it doesn't start anymore. I think it may be the safety switch at the clutch pedal. Does anyone know how to replace or test? Could it be anything else? It's not the battery as I have full power (dash lights come on, headlights work). I first had the problem yesterday, but after about 10 tries it eventually turned over and fired up. Any help would be appreciated. Thanks, Pete

I believe that switch Should be on the clutch petal. To test it first remove the blue/red wire at starter solinoid so truck cant start then go under dash with test light and check the wires going to the switch. You will need some one else to hold the key in the crank position will checking for power to clutch. This is assuming you have some basic wiring skills. If you are not getting power to switch then it may be a bad ignition switch, Ford did have a problem with these.

Thanks for the info. I think I figured it out to be a bad ground wire. Thanks again.