Backlash , Any suggestions ?

[JAZZCNC]

Nothing to do with Mach3 so forget that.!! . . . . They are correct thou that those motors are more than good enough when run at that voltage and with those drives.
It's a common mistake to blame motors and go for larger motors only to find out they weren't the problem and now your performance is less.!!

If really is loosing steps(I don't think it is.!!) This will be down to setup with motors being over tuned or mechanical issue causing binding.
My own feeling is that some coupler or pulley is slipping.? Missed steps tend to be one of two states.? Incremental showing slowly over the course of job in tiny amounts. Or Random with no ryhm or reason.?
Incremental often comes from wrongly setup motors/drives. Random from Electrical noise or poor wiring.

Give us some info on the tuning for each axis. Also Info on the Pitch of pinions or screws etc.