Will the DCC equipped Forney and other DCC locos run on a DC layout?
Yes.
As long as no one changes the programming in the DCC chip; I changed the address on mine and found it no longer would run on regular DC.
I was having the same problem of getting my engines to run on DC again after running on DCC. They just sat there. After thinking about it for a little while, I went back and reset the CV # 29 to the factory value of 6. And guess what; they all now run fine on DC again as well as DCC. Hope this works for the rest of you who may be having this problem. :)