Take a look at the magnetic roller of the toner cartridge if have not a missing toner band on it. And if is not from there it is from laser unit who can have some dirty on window.
For the last week, my printer started to print documents with a single vertical line that does not print, like if no information was sent to print anything there (WorkCentre 3215).
As a picture worth more than thousand words... See the red arrows on the text. The scan of the printed picture (on regular paper but scan is pretty horrible in fact) talks by itself!
Few solutions I found there were for other printers that does not look similar (as for tuts at least...)
I removed toner and drum to clean them just in case (just with a dry tissue): drum was dirty to one place but not that much. Anyway, nothing changed, maybe worste...
Of course, line always appear at the same place..
Any suggestion as for cleaning or things to check?