furnace not lighting/co detector

Well, it is working again. Dumb luck, idiotic persistence? I hadn't found the on/off switch previously, which enabled more rapid on/off tests than using the tstat. (thanks to bryant rv guides) I disconnected several leads, took out the electrode, tapped on the gas valve, etc.to no avail, although I did notice some change in the operation (it was running the fan longer, for example). Then I started messing around with the stereo, which led to me pulling fuses so I decided to pull the furnace fuse. I had pretty much given up but I gave it one more try. I heard a distinct click after the purge cycle and voila, ignition! Seems to work correctly, but i will keep checking over the next few days. I'm guessing at this point but maybe tapping the valve or resetting the fuse unstuck the gas valve. Thanks for all the advice!
I found the bryant rv guides here.
http://bryantrv.com/docs.html#google_vignette

Thanks for the Bryant RV link looks like it has some phenomenal information and with a little persistence much can be resolved.