Paper Creases or Curls
Paper Creases
Is paper loaded correctly?
If paper is not loaded below the load limit line or the load limit guide or is loaded obliquely, it may crease.
Are you using paper that has absorbed moisture?
Replace with appropriate paper.
Are you using appropriate paper?
Check usable paper, and replace with appropriate paper.
Do creases form when you print on plain paper or envelopes?
On the printer driver, change the setting of [Wrinkle Adjustment]. Setting to [On] may solve the problem.
[Finishing] tab 
[Advanced Settings] [Wrinkle Adjustment] Select [On]
[Advanced Settings] [Wrinkle Adjustment] Select [On]Change the setting of <Wrinkle Correction>. Setting to <On> may solve the problem.
Do creases form when you print on thin paper?
Change the setting of <Special Deliv. Mode>. Setting to <On> may solve the problem.
If you select <On>, the print speed may be slower.
Paper Curls
Are you using paper that has absorbed moisture?
Replace with appropriate paper.
When the current setting of the paper type is <Plain L>, change it to <Plain L2>
When the current setting of the paper type is <Plain L>, change it to <lPlain L2>
Do creases form when you print on plain paper or envelopes?
Set <Curl Correction> to <On>.
If you select <On>, the print speed may be slower. Also, printouts may be faded.
Are you using appropriate paper?
Check usable paper, and replace with appropriate paper. Also, specify the paper size and type settings properly.