Aporte original por: Philip Cowhig ,
short version: fixed this by finding paper jammed in 2 separate places. long version: Had 6000 and then 6001 error on MG7751. Paper had been repeatedly jamming at back of paper tray. First solution was to remove paper tray and then turn over printer on its side to find jammed paper underneath at rear. But that wasn't enough and I still had the 6000 and then 6001 error. Going deeper I found that I could remove the panel at the rear of the printer AND another curved component just behind that. This revealed another jammed sheet which was easy to remove. The two printer pieces were easy to put back in place. Then I had to restart the printer, after which it did that Canon thing of clicking a whirring for a few minutes before finally printing again.