I have an HP 660C. When I put single envelopes in to print, they now print backwards. Usually you put the envelope in with tab up and to the right. Now I have to put it in with the tab to the left in order to print properly. This is no big deal but I wonder if it will eventually cause a jam. I had the printer repaired recently (loud bangs when printing). I don't remember if the envelopes have printed properly since then or not. What caused this odd problem?