I have always swapped the problem car SIO board with a secondary controller SIO, never the master. Having said that, your situation seems odd for this known problem. Typically it's only one car out of a group. I have a ton of groups on service and it always been a secondary or non decision making 3rd controller with overhead problems. Oddly enough, after making the swap, the car receiving the suspect board wouldn't have issues then moving forward 80% of the time. If the problem did walk, then I would throw a new SIO in and was always good after that. Never needed any $$$$ software fix. Let me know how your situation turns out.