That seems odd to me. When I switched to the UC100 from ppt the settings carried across almost perfectly.

Right! I think I see now.  The original maxnc units appeared to require quadrature drive from M3 because they didn't have any sort of proper stepper drivers. Ugh! So there is no way a motion controller will drive it because they all assume the use of a modern stepper driver that just needs step and direction pulses.  I think you will need two things. First a set of stepper drivers, one per axis, that can drive your motors.  Second a breakout board to interface between the UC100 and the drivers. Can you give more information and photos of your machine?

Bummer.

So, my best bet is spend another $200 and get the general overhaul refurb kit.  Controller board, motion control boards, servos, power supply, and whatever else they throw in the box.

The servos are perfectly good, but they have 8 wires, while the "kit" servos have 4.

(sigh) If you wanna play, you gotta pay.

I've found some pics of the machine and I see on the back of at least the X axis drive motor there's what may be an encoder.  So maybe the motor had 4 wires and the encoder another 4.  The motors will be a standard NEMA frame size and could be replaced with steppers at significantly lower cost than servos.  Actually if the "refurb kit" motors only have 4 wires they must be steppers anyway - hardly any point in using servos on a tiny machine like this.  Modern steppers should have plenty of torque for it.

If you bought the UC100 already, then you need a breakout board which should be about $10, 3 steppers at ~$35, and 3 drivers at ~$20 each.  Look at https://www.omc-stepperonline.com/hybrid-stepper-motor for a good motor and driver supplier - I have always found them very good.