Another trick...before turning it on, open the upper paper tray (see pic), then close it after printer starts up. This seems to stop the 2 light blinking problem. I don't know why. This has been working for me for 2 years

Get a can of compressed air and blow out the paper path areas. This fixed mine, after it ocured to me that maybe dust or small debris was setting the paper jam sensor off,

Blow out the paper feed area with a can of compressed air. This fixed mine after I was in panic mode. There must have been dust or some small, unseen debris setting the sensor off. Hope this works for you.