When printing, there is a black stripe on the right side of the page. What is causeing this?

If the problem appears when printing a page from the computer, it is most likely a bad drum unit in the machine. The only way to fix this is to replace the drum unit itself. On your model, I believe the drum is part of the toner cartridge.
If the problem appears when you make a copy by placing your original in the feeder but not when printing from the computer, then the problem is dirty optics. The next step in troubleshooting the problem is to make a copy off the glass, bypassing the feeder. If the line is still there, you will have to open up the optics and clean it from the inside. If the problem goes away, there may be something on the "**** glass" of the machine.
The "**** glass" is a small strip of glass to the side of the main piece of glass that you lay your copies on. It will be a strip that is separated from the rest of the glass, and is about 9 inches long by about an inch wide. This should be cleaned really well to insure good copies. Do NOT spray glass cleaner directly onto the glass, as it will run under the glass and cause more problems. Use a high quality lint free towel and spray the cleaner onto the towel. Believe it or not, an old T-Shirt is excellent for this.
I would suggest cleaning all of the glass on the printer on a fairly regular basis, depending on your usage levels. For most home office users, this would be about once a month, for professional usage in a normal office environment, I would clean it about once a week.

The first thing I would try is to fix the corona wire. Here is a link to Brother's website outlining the process (clean corona wire).
What you need to do is pull out the drum and look for a blue tab on the top of the cartridge. Slide that tab back and forth along the wire and see if that clears things up.
I have had some luck cleaning the drum when I get black streaks but I have also hear this can be dangerous and make the problem worse.

My problem was that the corona wire cleaner was not tucked all the way to the side. Wherever the wire cleaner was, there was a big black streak. Corona wire cleaner on my 2270dw is behind the drum. Thanks cirvuedoc for the *hint* to fiddle with the corona cleaner!!!!!!!