Amiga 4000 mainboards are becoming rare these days, and are difficult to repair. But there's hope in sight. A lot of hope. In fact so much hope that you can almost grab a new one! Yes, we can make this happen!
Paul Rezendes from California, USA, has started a funding campaign to have PCB data files professionally recreated from an Amiga 4000 mainboard, and publish these under open-source license.
(This does not include any boards actually being produced - it's only about the data files required to do so.)