Thanks Group. Some interesting suggestions to explore.?

As to some of the suggestions, the locos are not metal. Just Atlas n scale models with decoders I installed and MT couplers. I think they are NCE decoders.

The two reverse loops are quite some distance apart. No chance of the consist crossing both at once. I have had the situation where a second train enters the reverse loop while another is in the loop. In this instance it simply shuts down until I move one of the trains out of the reverse loop.

This consist is not elephant style although I doubt that is an issue with these particular locos.

The FrogAR's are protected by a PSX. I increased the trip point current on the PSX as suggested in the DCC Specialities documentation but it still hesitates.

I think my next move is to break down the consist one loco at a time and see if the hestitation persists. If it does it would suggest a loco issue, I think.

Thanks again. I will report back after some experimentation............George.?