A while back I got stuck repairing a Staples SPL-710SH shredder. The story can be found here.
I put it aside because not only did it have an electrical problem, one of the gear's teeth was worn down. I tried futilely to try and find a replacement. Then I found this great youtube video on how to "repair" the gear. See here if you're interested:
Now that the gear was fixed, I had to figure out the electrical problem. When I put the paper in the slot, the shredder motor would not activate. Then I did what I should have done the first time which was to remove both IR emitters and make sure they were outputting light. I used my remote control sensor card and placed it right up against the sensors. That was not possible before with the sensors still mounted in the machine. One of the emitters turned my sensor card a very pale orange. I could not detect any response from the other emitter though the voltage and current going into it was correct. Then I combed over the specifications of all kinds of IR emitters trying to find a suitable replacement. Then it occurred to me to just find an old remote control, take out the emitter, and put it in the shredder. And a little to my surprise, that fixed the machine.