Update
Updating database... Please wait.
Friday 26 January 2018 at 04:07
Sounds like this is a relatively recent development? If not, please clarify.
Suggest you open up the backbox and re-seat the connectors on the sound board, as well as the other end of the cable. If that doesn't help, try re-seating the socketed chips on the sound board. It sounds like an oddball ...
Source: http://pinside.com/pinball/forum/topic/diner-strange-sound-behaviour#post-4195946