You are probably here because you own a Chamberlain, LiftMaster, or Craftsman garage door opener that's not working, and you are reasonably handy and resourceful. You've found out (from http://www.bearcatco.com/helpgifs/chamberlain_troubleshooting.html or the equivalent) that the five LED flash error indication is supposed to denote "RPM sensor or motor overload" failure, and you may have already confirmed that your motor isn't the problem. (I did that by taking the chain off the sprocket, unplugging the RPM sensor, and finding the motor then readily turned a short while before stopping: warning, you can bend or even break the limit stops in doing this! Keep an eye on that portion of the opener while trying this trick, and be ready to pull the plug on it.) Based on this, you now suspect your RPM sensor may be faulty. You took out the RPM sensor and had a good look at it, finding the code 14LG410A on the little circuit board, and that's how you ended up here.

I jumped the gun and bought this little guy at that point, later learning that my RPM sensor was not the problem. I'm here to warn you that the 5 LED flash is no guarantee that you do. In my case, there was a cold solder joint to one of the relays on the logic board, making it such that the opener could not reverse direction. This caused the logic board to prevent any (perceptible) motion of the motor at all, and to interpret the problem as motor overload and flash five times. Before ordering a replacement RPM sensor, you should take a good look at your logic board for cold solder joints. You may also want to manually move your limit stop sensor (the little thing with two metal leaf contacts, on the screw drive) to the middle position and see if your opener then moves (with your RPM sensor connected) until it hits one of the stops. If it does, the problem is unlikely to be your RPM sensor. Typical symptoms of a failed RPM sensor are those observed when you unplug it: the motor will turn for a second or two, then stop. If you find your garage door opener does this, then stops, even with your RPM sensor connected, your RPM sensor might be bad. I'm no garage door opener fix-it guru, but this is what I've learned from the school of hard knocks!