I get popup saying actual paper size in tray and specified paper size are different - but they're not

Won't work. I did a reinstall and no luck. It must be the roller because I do 2-sided flyers and never have a problem with side 2, so I print 3 sides.

To print 100 flyers, I print a 1 pixel white image 100 times, open and close drawer a few times when I get the popup, then put the paper back in and print away with no trouble, almost no trouble. I might get 1 popup out of the 100 sheets when doing the actual printing. By printing the white pixel first, it doesn't matter if the paper slips because nothing is being printed.

Reason I print a 1 pixel image instead of just printing a blank page with doc is because even blank "apparently" uses toner. I do 100 blank doc pages and the toner levels show as going down, but a 1 pixel image doesn't make any noticeable difference to the levels.

My printer is the 1320c color laser printer. A few weeks ago I started having sheet feed problems. I use standard 8.5 x 11 Staples brand laser paper (24lb and 28lb) and I might be lucky to get out a dozen copies of something before I get a popup saying "actual paper size in tray and specified paper size are different". I just open and close the paper tray and it resumes, for maybe another 5 to 12 sheets. When I get the popup, a couple of the last few pages that came out show that the paper feed is slipping. I tried cleaning any rollers I have access to, but no help. I've even tried not fanning the paper and no difference. How do I get this fixed? Do I need to replace a roller? It shouldn't be the paper because I've been using the same paper for a while now. I did try Zellers brand laser paper once, but it was useless. I'm not sure, but I think it was jamming, so I quit using it.

I also (all of a sudden) started to have this problem out of the blue  - opening and closing drawer resumes the print job but this is a pain  - I am trying to find out how to manually  reset to factory defaults hoping that will help