Hi splt7190,
It’s suggested to use the provided PETG cura settings. You can see details after you install the Snapmaker J1 Cura plugin. Install guide: Beta Version - High Speed Firmware, Cura Profiles, PrusaSlicer Profiles
You don’t need to remove the top cover of the enclosure when printing PETG. Only need to remove that when printing PLA.
We are preparing self-maintenance documentation. Currently, we finished Chinese version. We will translate them into English and share with J1 community before Nov. 25. If needed, we can take some short videos to show the replacement process when we receive support tickets about troubleshooting.