Hi Cliff,
Since it worked sometimes and you have worked over the RJ phone cords, I'd look at the DCC signal coming into the ACM.? Since you probably don't have a scope to look at signal integrity, I'd connect your DCS210+ directly to the DCC input connector on the ACM with a short run of wire without the DCS210+ going to the rest of your layout.? Obviously, this isn't useful, but at least you will know the problem is DCC signal integrity.? Then we can go from there.
Allan
