Had the problem with a SX440W and after some hours trial and error and chatting with the support, who told me to send it in for 95 Bucks, I finally found the error. I had a real paper jam and pulled the paper out backwards. At the bottom of the top paper feed there is a black plastic stick, which is the paper jam sensor. When pulling out the paper, the stick did not switch back. I opened the printer top (2 screws) and put the stick back where it belonged. After that it prints like new!