Hi Jazz,
Since the upgrade to the NEMA 23 motors, I have started to get one of my Axis dropping steps, I think I have traced the problem to lack of power from my Power supply.
When I made the change I did not change the settings on the Drivers, the old NEMA17 motors where 2.5 Amp and the new ones were 2.8Amp so rather than messing with the drivers I left them at 2.5 Amp. I then started to do stuff on the CNC and noticed that the X Axis which is slaved to A was dropping steps. Checked the Tightness of couplings etc. but could not find a fault. Decided, as I had the machine apart, to change Drivers to 2.8Amp. This has now resulted in X & Y Axis dropping steps. Aha I thought not enough power, I only had a 10Amp power supply. I have bought a new 25Amp Power supply and I am now waiting for its delivery tomorrow. Hopefully this ill have resolved this issue. But really, the thing is I'm retired and building this on my own without a contact to bounce problems off and was looking for such a person, someone who would not mind giving some advise when required.