experiencing Z axis issue/Autohome speed control???

I have a taz 5 that has been working great for the past few weeks, but randomly started to run into problems with the z-axis motors. Basically, I can jog in x and y no problem. The z direction however, only moves in 1mm increments without making a humming noise sounding as if the motors were failing. My jog speed was set to 20mm/s.

I leveled the setup (no results), lowered the jog speed to 5mm/s (no results), and checked the x-axis belt’s tension (no results). Finally, I tightened the motors for the z axis and this let me move in 10mm increments without binding up and making that sound. I can now go up to 7mm/s jog speed without binding. While this was an improvement, I still can’t auto home the z axis because that spins the motors much faster than jogging.

If you know any other things to try let me know!

If you know of a way to manually control the autohome’s speed it would be great to hear.