Printer alignment may be the answer but at 600 dpi and with some apps printing it OK - less likely. But try in the printer s/w there is sure to be a printout to prove it, maybe an adjustment.

I would say your best hope is to stick with downloading then printing. with Noteworthy Composer - if there is an option to save as jpg - try that, then print with the best printing software. A bit of a bind but...

You could try updating s/w and printer driver but if you have success one way I would stick with that.

Canon misalignment but it refers ti vertical lines.

another webpage

Then there is the subject of the paper, are the guides that feed the paper snug to the edges? is there a stack of paper in the tray ( or shute) or only one? My current printer has a tray and it can do funny things with only a few sheets left. Though lately it is better, something to do with paper and moisture content (I think).
Try thicker paper just for the music, it will be more robust too.