Paper Jam while double sided printing. MFP M479fdw

[AjCaresLess]

Hey there i have a HP Color Laser Jet Pro MFP M479fdw, It recently got an OEM fuser replacement about a month ago and everything has been smooth. We use this daily at our office and we never got any issues but on friday right after it successfully completed a double sided print as it normally does. The printer ran out of paper so we added more paper to the printer but we added a little bit more than it could take, so the printer notified us that there was too much paper in the tray. We removed most of the paper and started printing as usual and when we printed a double sided document it got jammed at the back, we didnt think nothing of it we cleared the jam and attempted to print it again. Thats when i noticed once the first page prints and it goes back in the printer for the other side it jams, so i decided to print on a single side and it worked with no jams. This is very strange because before that first jam we only print double sided and no setting changed. Please anyone with any idea on what the issue is and how to fix it would be greatly appreciated. I volunteer at a non profit and they print alot and like to print double sided to save money , this issue is pretty problematic for them because of they will have to keep printing single sided for the time being till this problem is solved despite spending so much money on the fuser replacement recently.

[Repairatrooper]

If it jams when pulling the paper back in then there might be a dislodged paper guide in the duplex refeed assembly. 

[AjCaresLess]

Thanks for the Reply, how could i fix that issue ?

[Repairatrooper]

You need to ensure that all guides are in the right place and that there are no fins broken on any of the guides.