Hello, I have a GBC Shredmaster 6120S

Though I only work with Fellowes shredders this sounds like a paper feed sensor issue. If your unit has a mechanical paper feed sensor you can try to jiggle it in and out to see if any paper may have become jammed behind switch. If the unit has an electronic sensor it may simply need to be cleaned with a Qtip dipped in rubbing alchohol.
If neither of these help your paper feed sensor or your pc board has gone bad and you will have to contact your manufacturer for further parts availability.

WE HAVE A 1026 S THAT WAS STOPPED WHEN WE GOT IT.
IN DISASSEMBLY, WE FOUND THAT THE METAL WORM GEAR FACES A PLASTIC WHEEL WITH A POLYCARBONATE RING OF TEETH, AND WHEN THE SLOT WAS APPARENTLY STUFFED TOO FULL, THE BIG GEAR STOPPED, BUT THE MOTOR MADE THE METAL WORM GEAR KEEP TURNING, WHICH SHEARED OFF THE POLY TEETH OF THE PLASTIC WHEEL.

DUH, IF YOU ENGINEER SOMETHING TO REALLY LAST, YOU PUT METAL GEARS TO METAL GEARS, IF YOU ENGINEER SOMETHING TO HAVE PLANNED OBSOLESCENCE IN IT, YOU PUT METAL TO PLASTIC.

MAYBE YOU CAN ORDER THE PLASTIC GEAR, DISASSEMBLE IT, INSTALL THE NEW PLASTIC ONE, AND MAYBE MAYBE IT WILL WORK RIGHT, BUT IF IT DOES, BE EASY ON ITS FEEDING, SO IT WONT HAPPEN AGAIN.

I AM SEARCHING THE INTERNET FOR A 1026 S PLASTIC GEAR FOR THE SAME PROBLEM/

HOPE THIS HELPS

BRADY

Replace the main printd circuit board.