I have new concerns after reviewing the wiring diagrams. The motor encoders go straight from the motor to the "master PCB," I was under the impression that the drives usually handled the encoder feedback, but if these motors need to communicate with the PCB I have pretty limited options:
Repair the stock control PCB and drives, downside is I'm unsure what does and doesn't work and this looks like it would be a nightmare.
Replace the motor drives (with A-M-C) at $400+/- per axis, the easiest method if I can just rip out the stock garbage and plop new drives in, downside to this is that once the motors croak I'm stuck with drives that run motors I haven't had much luck finding replacements for.
Replace the motors and drives (Zapp Automation 1.3kW) at $1000+/- per axis, most expensive upfront and is pretty much my original plan.