Royal CIA12 crosscut shredder overload light came on.

They all have a way to get into them. If you do get inside you may well see shattered nylon gears!

Disassembly videos

https://www.google.com/search?q=10+x+royal+crosscut+paper+shredder+disassembly

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Has it got too hot

Some shredders aren't designed to shred anything more than paper. Credit cards, staples, paper clips and the like could have jammed it up. Try running the shredder in reverse and oiling the blades. More help with paper shredder oil here: http://hubpages.com/hub/Paper-Shredder-Oil

If you can't get the paper shredder up and running, it looks like you might have to pick up a new paper shredder. Paper shredders can be pretty cheap though, great guide to cheap paper shredders here: http://hubpages.com/hub/Best-Paper-Shredders

in the middle of the paper enterance clean sensor

Check and try cleaning the "eyes" in the paper throat... if that dosn't fix it it could be the pcb inside...call Royal at 1-800-524-0799 for parts help.

call royal spare parts department at 1800-222-2310 they will ship you a gear for about $6 + shipping
it will stop the clunking