Take all this with a grain of salt, as I'm not sure I know what I'm talking about: I've read that even stable video signals (like DVD players) need to be synced to a TBC if there's more than one of them. I'm not sure how one would go about that. Hopefully someone else here has a better answer.
You might also try giving NewTek a call - they still repair Amiga Toasters, though I'm not sure they'll be able to do tech support over the phone.
