elmcannic, I did reduce the Open High Speed, and added tension to operator belts which did keep the car from shutting down.
However, the fault still appears, but oddly does not shut down.
Not sure how it can go from shutting the car down, to not shutting it down with the same Door Operator Fault appearing.
I did not adjust "Open Backlash Time", but can try that tomorrow.
One other piece of info, not sure if it matters, is that this is a Service Car, with a very high Cab ceiling. Therefore operator arms are very long.