[Prints start printing off axis halfway through]

http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide

See 4th image down on the left.  Sometimes this causes leaning - sometimes sudden shift exactly as shown in  your photo.  This is very common and easily fixed in a few minutes.

Most likely it's the pulley on the stepper motor.

 

Thanks, that's a very helpful resource to have! Didn't know it existed!

Turns out the bars were slightly not even and causing the belt to slip.

Consequently it looks like they've worn down a few of the notches so I'm going to have to get a new belt to replace it with.

[Prints start printing off axis halfway through]

This has been a problem for a while now.

Whenever printing anything more than a few centimeters tall, the printer shifts and starts printing in a totally different position than where it started. Usually finishes the print, just in a different area than where it started.

To clarify, the misprint is where the "M" gets cut in half about halfway up.

Picture of example attached.