Thanks for posting your playthroughs of these games. I'll let you know when I start work on each game if I require any additional info. And thanks for sourcing a scan of the instructions for 3D Blast. That's awesome!
Great news on getting hold of Sonic Spinball. Despite the display issues , it's really helpful to know you could still use it as a reference to playtest my builds of the game to ensure the gameplay is accurate. I'm not sure when I'll start working on it, but I'll let you know when I have something you could test. In the meantime, it would be really useful if you could provide some gameplay footage so I can capture the audio. The videos online do not have the best sound quality. Also, not sure how easy it would be, but if you could also try to include in the playthrough a few runs with as little actions as possible so I can create a loop of the background music without the sound effects?
It's unfortunate your SegaSonic games don't work. Regrettably I don't have experience repairing LCDs, but hopefully others in the community who do can help.