Follow the phase wires from the driver to the back of the machine to see if your current large one is on X or Z. Langmuir has shipped them both ways.
There is some guidance from Langmuir here on swapping drivers:
The documentation on swapping drivers is here:
https://www.langmuirsystems.com/mr1/assembly#mr1-9
All of the drivers have documentation for the pins printed right on them. Take a photo of how it was wired before you start moving pins around in case you need to check what color wire had which role.
Good luck, hope the driver upgrade fixes your issues.