I don't think it's a warranty issue, I've always found Bachmann helpful with spares etc, and I hear that Hornby are the same. I'm very much in the camp that says remove them, they can cause problems. However with my American stock with plug and play sound I've just left the all the confetti in place, and never experienced a problem. Bachmann can be very sneaky with theirs some of them are hidden out of sight . As Doug says remove them to save you having to remove the body for a second time.