If you are having a lot of issues with your printer or otherwise need to perform routine maintenance on it, I recommend watching this video.  This guy put together a pretty good guide to general maintenance on 3D printers that is applicable to many machines.  You won’t necessarily need to do all of it (or feel comfortable doing all of it, he really goes into it), but it’s a good guide.  I also ended up getting his reference book that he plugs at the end.

3D Printing Failures