S2500. Have users manual, know how to clean / condition with wd40. After last paper jam, now getting paper folded on right top corner. Some coming out wrinkled. Ran cardboard thru and can see a scuff mark on the right top edge so suspect there is something left inside. Stopped paper travel at several points and all OK except after it passes thru the platen. There is a roller back there down in the bottom. How do I get to it to clean / inspect???