Superbrain schematics

Hi Andrew. I have a SuperBrain QD that I had up in the loft. Unfortunately the display no longer works as the graphite core that fits into a donut coil attached to the side of the Video case has snapped in two places. Though the display appears to work no characters are visible. It does boot and if the dir command is entered it is apparent that it is attempting to display the output as the cursor moves across and down the screen. I have tried looking for spares via Google but no luck. Hopefully knowing what the gizmo should do I could fix or replace it. Thus if you have still have the schematic package available in digital or hard copy, I would be grateful if you could let me know. I am retired and wrote business applications in the 1981's and am curious to revisit them to see how things have changed since the heady days of CPM 2.2. I realise that your post goes back to 1998 but it would be great to receive a reply. Regards Anthony