Malfunctional Derringer Car Alarm, Hints?

[grant lyon]

Have a "Derringer" Model 8300 by Vehicle Security Electronics malfunctioning in a '84 Carrera. Can start car with normal override switch when we reconnect the battery. But, with motor running, the horns stay on and running (side) lights stay on. Pulled the horn rly, so we can at least start and drive without the horn. I'm inclined to tear up the main alarm module to look for stuck rlys, but owner is afraid this will disable the car. I can probably figure out how to hotwire/neuter the starter disable. Any others with experience with Derringer alarms with similar symptoms?