I have been trying for a long time to ascertain the possible causes. For years it only happened in one block, and then of a sudden it spread. To me, this means something changed, but I can't figure what. BB suggests I try getting a Rev L, but I hate to spend train funds that can better be spent elsewhere. I have to try various combinations of settings.
It's odd that only the whistle softkey sounds do this; I haven't noticed it with any other softkeys.
Before anyone says, I do not have two feeds to any block and there are bulbs on TIU outputs and elsewhere.
