The electromagnetic principle they use in these, like many other types of devices of this nature should last quite a few years. Someone on here had one that died. He ripped it apart and found a lead wire that had come loose. He soldered it back on, and it's making bubbles. I would think it was a vibration issue. I've used a lot of these types on bowl feeders and such.
Over time, the motor materials for these will degrade and get weaker, but that's a long, long time!
You'll run into more physical and mechanical issues as Bill has stated, but that would be about the same for any of these types of devices.
RC51 has had two. One lasted for 4 years, the 2nd, not so long. Don't know what caused them to croak tho.
