Homing X and Y OK, but Z only moves downwards from current bed position
I am having a problem with an Enjoy 3D Printer. I am using Repetier-Host 2.2.4 and Repetier-Server 1.4.2 on Linux Mint. When I attempt to home the print head, the X and Y homing seems to work correctly, but the Z direction behaves strangely. It will simply move the bed downward a few millimeters every time homing is commanded, and will continue doing so until it hits the bottom frame of the printer.
This printer was working fine until a couple days ago where I had some problems with the extruder and had to clear the nozzle. I am unsure if that has anything to do with this problem.
I'm very new to 3D printing so bear with me as I learn. If more information is needed I will provide it. Thanks for your help.