If it ain't broke, don't fix it?
aint that the truth.. learned that the hard way a few years back... cleaning all the grime and gunk out when doing some home plumbing... thought, "well while i have the drain unattached i might as well clean some of the other junctions that look gunky"... and of course the gunk was the thing keeping half of them from leaking in the first place.
honestly, i didnt even take my flame sensor out of the furnace. shut power down, had reasonable access to reach in with a light sandpaper and just gave it a few strokes all around. went from having the occasional "why is it so darn cold" in the mornings when the furnace was told to kick in to now having no problems so far... hoping that little productive minute spent cleaning it gets me through the winter.