A1260 is on to something. If the thing is totally dead (no picture) take it to a TV repair center and explain that it's an old monitor that uses TV signals. If they get it working in composite mode then there's a decent chance it'll be fixed for other modes. They can test composite with a DVD or VHS. RGB might me kinda hard for them to test unless you want to leave your Amiga and they want to bother.
