Hi Fitchie,
I don't have your focuser but here are some "general" suggestions on focus.
Just looking at the parameters you have selected I see you are using the Polynomial Algorithm. Is there a specific reason for selecting this? In general, Linear 1 Pass will deliver better results.
I see also that you have Sub Frame selected so you are using a single star for focus. From the CFZ tab you have a 107mm scope at F# 6.54. I would suggest using multiple stars for focus by selecting Full Field.
You have an initial step size of 3000 on the mechanics tab but CFZ tab is showing a CFZ of 8. So something probably isn't quite right there as these 2 numbers should be comparable. The CFZ will default all but 1 parameter from your Optical Train. So on the CFZ tab you have Step Size set to 5 microns which I think is the default so I'm guessing you haven't measured it? It would be worth setting this correctly as it will give you a clue as to what to set the Initial Step Size to.
As far as backlash is concerned you have driver backlash set to 5000. I can't say if that is right or wrong for your setup; you'll have to measure it yourself. Its worth having a read of the Backlash section in the manual if you aren't familiar with it.
I would recommend using the Focus Advisor (Advisor tab) and let that default most parameters for you. You will have to setup Step Size on CFZ tab and backlash yourself (or AF Overscan if you prefer).
Here is a link to the Focus section of the Kstars Handbook...
docs.kde.org/trunk5/en/kstars/kstars/tool-ekos.html#ekos-focus
If you are still having difficulties post a picture of the V-Curve along with the parameter settings as that is useful in seeing what's going on.
Good luck!