Lets not forget the recent 767 that waited for a fighter to come up and do a gear inspection before landing.
Used to fly an aircraft that at times had trouble getting the gear to lock in the up position, recycling used to do the job, but to find which gear was the problem pull the gear control CB and the leg giving the issue would extend, tower on a fly by could then tell which one and a quick turn around by maintenance resulted. Gear indication only had three greens and one red, so you couldn't tell which might be causing grief.