Canon BJ-200ex - Manual (Page 36)

Always set the paper thickness lever before and after printing on
thick paper or envelopes.
If you are printing documents with high density graphics or
ink and the printed pages are smudges, try setting the paper
thickness lever to the right position. This unit moves the
print head unit further from the paper. Print quality may
diminish slightly, but the smudges should go away.
Setting the Paper Selection Lever
Set the paper selection lever to the proper position before
loading paper. There are two positions according to paper
type:
§ The back position is for normal plain paper or transparencies.