Need some help with TMCC engine and I am hoping to tap into some expertise. I have a 18193 which is the unpowered f-3 in the Western Pacific set. This unit has all tmcc functions but is not powered. Manufactured 1998. At this point, it doesn't respond to any tmcc functions. Horn and bell work in conventional. Now the puzzler, when I put it in program mode and hit the set I get sounds. If I leave it in program, I get sounds. I tried replacing the receiver board no change. Any ideas?