How to resolve inconsistent check printing
If your checks sometimes print correctly and other times the formatting is off it could be an issue with your printer.
It is possible that your printer needs a cleaning.
You can also try to adjust the check layout so that it prints better when this happens but still prints well when it prints normally. This may be hard to accomplish when it doesn't always print the same way. This is not the recommended solution as your check data is always sent the same way so it should always print the same way.
If possible, test the printing on another printer to see if it prints the same way.