A:AnswerPop the back tray and you will see the mechanism for 2 sided printing. This is often the culprit in your situation. There will be an easy release tap in the back to make it easy to get to. Might I suggest you try using a different paper. Hammer mill is much pricier I get that but the fact they boast a 99.99% no jam rate and I have yet to have a paper jam using their paper in the decade I have been is a testament to that statement.
A:AnswerMine did also a couple of weeks ago.. no warning either... I bought a new one for $145 at Best Buy which less than a repairman would have charged.