- For inquiries on the mainboard, please reflash the firmware before buying replacement. Your mainboard is all good as long as it shows Elegoo logo.- for shorted mainboard, main connect harness cable - please choose the "Lower Half" option. It might cost more labor to strip the machine down than ship some extra parts.- For inquiries on Z axis, lead screw, please use the "U Frame" option. The same reason above.- for plastic parts, please print them on your own. Spool holders, monitor holders, R buckles, X/Y tensioner covers are made of plastic. Please print them and PLA is strong enough or use a zip tie. We uploaded some to Thingiverse:https://www.thingiverse.com/limuzhi/designs Free STL files for Neptune 4 series cable holder, organizers:https://www.thingiverse.com/thing:6217095 https://www.thingiverse.com/thing:6464725 https://www.thingiverse.com/thing:6203991 https://www.thingiverse.com/thing:6199076 https://www.thingiverse.com/thing:6249358 Compatibility Guides for FDM fixup projects::* touch screen controllers are interchangeable among ALL these 7 models (firmware reflahsing is required)Neptune 3 Pro, 3 Plus, 3 Max, Neptune 4, 4 Pro, 4 Plus, 4 max* main boards are interchangeable throughout the series:Neptune 3 series: 3 Pro, 3 Plus, 3 Max - same main board (firmware reflahsing is required)Neptune 4 series: 4, 4 Pro, 4 Plus, 4 max - same main board (firmware reflahsing is required)* hotend assembly is interchangeable throughout the generationsNeptune 3 series: 3 Pro, 3 Plus, 3 Max - all same hotendNeptune 4 series: 4, 4 Pro - same hotend Neptune 4 Plus, 4 Max - same hotend (input shapping added - accelerometer) - Lower half does not contain the PEI sheet, touch screen monitor, screen holder- U Frame does not contain hotend, filament detector