One of my SC2's started missing some switch throw commands. Five of the six switches attached to it worked just fine, but one did not. Might throw the switch several times in a row then start missing the "out" command. Figured the unit had a bad relay in it or some such thing. Just before pulling it out, decided to run a home ground wire right next to the unit. Problem solved! All commands to it work fine and it appears to react noticeably quicker.
My layout room is small and in basement surrounded by house ground wires and locos all work fine. Never occurred to me that signal strength would cause the problem I was seeing. Could be that the SC2's receivers are not as sensitive as the ones in the engines. I have now run a house ground wire within a foot or less of all my SC2's.
Thought it was worth passing this along.