Thank goodness for the backup procedures. Coming back to SJC the other day, my gear didn't go down when I moved the lever. I make it a practice to keep my hand on the knob until I see three greens and confirm out loud that there are three greens. In this case, nothing. No whirring of the motor, no clunking of the gear into place, nothing.
Slowed down and selected the emergency gear extension which removes the hydraulic pressure holding the gear up letting gravity (and the airflow in the case of the main gear) lower the gear. Glad that worked, or I'd be here reporting a +1 in the real problem column.
Something similar happened to me when getting checked out in the 182RG at Marine City, MI. We were headed back to home base from a nearby field (KPHN) and I had put the gear up, but noticed that the gear up indicator had failed to come on, though the wheels were no longer visible. At first I thought this was a "manufactured" failure courtesy of my instructor, but a quick look at the CBs dispelled that notion immediately. He told me to cycle the gear back down, and of course I did immediately. Down came the wheels, but no green. Though I don't recall doing it, I'm pretty sure we checked the bulb. Looking at the gear the instructor said he thought they were down and locked, but I wasn't so sure. I wanted to pump them down by hand, so we put them up again and pulled the circuit breaker. I pumped and pumped, long after the wheels were down, but still no green.
Finally the manual gear handle was too stiff for me to give it any more, so the instructor gave it one last hard pull, and... success! Green, down and locked. By then we were entering the pattern at home. I was still not too confident, so I landed as carefully as I could, keeping the weight on the mains as long as possible. It was really one of the nicest greasers I've ever done. We put the plane away and reported the failure to the maintenance guys.
It turned out it had indeed been a hydraulic leak - and we had lost enough fluid that it was almost a miracle that we were able to pump the gear down. Putting the gear back up a second time was exactly the wrong thing to do! We got very lucky that day... or rather, Bill (the owner) did, since gear up landings are usually harmless to the plane's occupants, just very expen$ive.
Since then I've had issues with my 177RG's gear system too, though no hydraulic leaks so far (knock on wood). Anyway approaching to land there's always the thought in the back of my mind, please G_d let the gear come down. Probably why I've never come close to forgetting the gear in many hundred landings in that plane. (Which isn't cause for complacency, of course.)