Unresolved Printer

My printer has started randomly shifting it's prints toward positive Y after about a week of good printing (possibly some x deviation too). Where is most likely the problem? Any ideas on ways to test it? I have a suspicion that the power of my garage might be cutting out for split seconds; Again, how would I test and correct that? Thanks for the help!

Problem: after some amount of printing it seems to change where it thinks 0,0 is, spewing plastic out over empty air or the wrong place. This happens multiple times, on a BIG print once every few millimeters. This happened once before when I moved it while it was printing but hasn't been a problem since then. Unfortunately it is in my garage so it is somewhat hard to monitor.

 

Tighten the belt probably

 

Few updates:

-All fans with holes on the outside checked and working (1 on top, one opposite on bottom)
-Belt made a very low note when pulled (seems like about right, could maybe be tightened, how would I do that?)
-Adding another surge protector didn't work (May not do anything, I don't know how they work, there is reason to believe I may be having split second power outages)

Computer driving it is REALLY bad. Could it be something with that. Also, I am fairly sure this began when I switched from a clear PLA to white (same company, first time testing white). Could that have anything to do with it? Again, any ways to test or possible causes are useful. Great thanks for any help!

 

I was reading http://forums.robo3dprinter.com/index.php?threads/shifting-layers-in-y-axis.4690/ and saw the part on clipping the part. The surface of my prints has been very uneven. Again, how would I test/ fix this.

 

Pictures of any print issues is much more useful than a description.

You should try printing from SD if the computer is causing issues.