I recently inherited a few of these. I don't know a lot about them, but what I do know is hard earned. What does the tool tell you under status/car and status/bank when this occurs?If LED DS11 on the MTV card is on it indicates which car is master. Off means slave and blinking means it is not talking to the master.If you are plugged into the master car then it will give you the FTR option under Stat-Bank. under FTR it should say Block operation, down peak, up peak or normal operation. Block operation means there is no dispatching to the group or hall button power. I had a lot of intermittent problems between the 3 groups that I have and a complete tighten down of all terminals on each controller made several of them go away.