Arnold did you try to adjust the small blue volume control up and down on the underside of the loco with any results? Hopefully it's an easy no or low cost fix (volume control wipe or loose wire). Good luck.
FWIW, I have a PS2 Railking Imperial K4 that every now and then and without making adjustments will zero out its volume in some or all of it's respective sound catagories (bell, horn, engine and accent sounds). Only fix I found was to use the DCS remote and enter the loco's menu sound settings and raise the respective muted volumes above zero. At first I thought the clickety-clack sound feature caused the problem but not always and some muting occurs randomly. Since I can't find a true cause eventually I might consider reloading the soundfile, but the as needed DCS remote menu sound adjustments isn't too inconvenient a process.
