Can you post your current config.g?
You'd change the wiring from E0 heater to E1 heater and then in your config you'd need to tell the firmware you've made that change.
@amcutem the “combined version” of the firmware is for Duet 2 WiFi and Ethernet. Use the ‘RepRapFirmware.bin’ from 2.05.1 and 1.26.1 release for Duet 06/085.
I think the Rostock issues that number40fan was referring to are the apparent high spots between towers, related to the mechanical design.