Slow My Z Axis Down (losing steps) -Mesa 7i96

Can somebody point me to where I can safely make a change to slow my Z axis down. It has been too long since initial setup for me to remember. During this last winter when I first get going and everything is cold, I would lose steps on my Z axis as it is going down to probe the material.  When this happens it crunches way past my upper limit when going back up. Not good. I looked in the HAL file, but I am too nervous to make any changes. I just would like some input before I go screwing my machine up trying to make an adjustment. 

Running on MESA 7i96 and QTPlasmaC. 

Thanks in advance. 

In the .ini file, sections JOINT and AXIS Z, max_velocity
It has to be same in both sections and it is in units per second, so mm/s or inch/s. Multiply by 60 to get by minute values.

That seems to have done the trick. Thank you. One quick question. You said it has to be the same in both places, but the .ini file instructs that one be double the value of the other. So I have it set that way. Should I have not done that?

Yes, just saw it is in PlasmaC section, so yes it has to be double in the AXIS Z section.

I am using QTPlasmaC, but I doubt that makes any difference, right?

No it does not make a difference, so all is OK.
They both use the underlying PlasmaC THC part.

QTplasmac uses external offsets. External offsets requires some portion of the velocity and acceleration to be apportioned to it. This is done with the eoffset ratio in your ini file.

With plasma we do some tricks because normal motion and external offsets are mutually exclusive.. So we use double the velocity and acceleration with an eoffset ratio of 0.5. this gives 100% of velocity and acceleration when operating whether cutting with THC or jogging.
Now QTP also applies External offsets to the X and Y axes for change consumables etc.