I've repaired mine to the point it is seeing the signal and keying the loop. My only problem is that the loop voltage drops when I plug my printer in to almost nothing and returns when I unplug it. The recieve light comes on when you plug the printer in and goes out when you unplug it. The Standby light comes on with power and flickers when I add a signal to the machine. I can see 60Ma on the loop with nothing plugged in and it dives under load.