I'm using a TriGorilla 2560 and Marlin bugfix 2.0.x, and two stepper motors that I'm using as two Z-axes.
For some reason, both Z ports, and the E1 port are being driven by the same stepper driver:
The problem is that only one port is actually working well, meanwhile, the other ports (one Z port and E1 port) make the stepper jag as in this YouTube video.
Also, there is a driver that looks like it is not being used by anything:
So I wanted to try to assign that driver, to the E1 port (and a Z port), and see how it goes, if it does fix the issue or not, but the problem is that I have no idea on how to do that on Marlin.
Under the pins section either of TriGorilla and RAMPS, all I can find are the definitions of the ports, so I can swap port usage, but not assign a specific driver to a specific port.
If it helps, here's my Marlin zip.