I have a brother MFC 8440 and the document feeder has never worked properly. It pulls the documents in slightly off line and causes the paper to jam before it gets to the scanner. It is out of warranty now. Are there any minor adjustments that I can make to get the feeder to pull the documents in straight?

try to clean the document feeder, i think there so many scratch of small piece of paper that why the printer is paper jam.

Clean the rollers with a rag with turps on it.

http://www.brother-usa.com/Support/?WT.svl=contact

Could be a sensor in the ADF, or the hinge on the left rear of the scanner cover is broken.

I got adventurous and removed the screws holding the document feeder. I then used a can of air and blew into the gears and then reassembled the feeder. It works perfectly.

change paper pick-up roller & paper stop roller in ADF

Whoaaaaaaaaaaa!!!!!!!!!!!!!!!!!!!!!!!!!! No need to da all that. Lift up the Doc feeder and look at the SMALL strip of glass, you will see a dot or something on it, clean w/alcohol. Voila taken care of. the dot ( pen mark, white out, etc...) makes a line because the document is Moving and that dot now looks like a line to the copier. :)

Can be a document feeder jam.
Also can be that you are trying to copy an odd size original that it doesn't have the paper-stock for. in that printer it can be caused by not having the paper trays set correctly or using the menu to force it to try printing on something like legal size paper when it only has 8.5/11
Try resetting the printer with a power off and make sure the paper try is set to 8.5/11

ITS PROBABLE THAT A CONNECTOR CAME OUT.REMOVE BACK CORNER PANEL AT FEEDER CABLE TO CONFIRM.

Have you tried manually rotating the ADF wheel back and forth, sometimes the sensors are OK but the rotators lose grip.