Hi: suddenly can't remove my Brother MFC J6710DW upper paper tray. Can't print on remaining paper in the tray, but can't pull out for paper reload when required. Ink levels are half full. Lower paper tray works fine. No error messages. When tugging on the upper paper tray it feels as though is has become locked. No evidence of paper chips anywhere, and as mentioned, the paper in the tray prints without difficulty. Just worried that can't reload when paper runs out. Read elsewhere that this condition is mechanical and can be corrected from the back of the machine, though that fix was for an entirely different printer, and am not certain where the repair could be done, front or back of computer. Help appreciated. Thanks, Jim1