You were correct, but it was an unfortunate combo for me. It was, in fact on coin op mode which does produce the sound! However, it turns out that the battery on the board was hosed, so it wasn't saving my settings. Whenever I reset the game with free play on, without the battery, the settings were lost, and I couldn't change them basically. Luckily for me, I remembered that I had a couple of untested coin-mechs inside of that Silver Strike 2009 bowling cabinet, and popped them into Gauntlet. The first one needed a little work on the lever, but I got em both in, and they're working great. So, cabinet is now 100% operational!
Additionally, while cleaning the cabinet, I found about 5$ in quarters, as well as some receipts from 1998 detailing the machine's weekly payouts for a period over the summer in '98 AND the big prize; an entire Dark Legacy upgrade graphics kit safely wrapped in a tube! Cabinet began its life as a Legends conversion, so it still has a near mint Legends panel overlay and artwork, but the monitor bezel is much appreciated, and now I've got two extra marquee's (ordered one when I first got machine).
The machine has taken in 177894 quarters in it's lifetime according to the counter, which boils down to: 44473.50 !!! It was making an average of 194$ a day at it's original location in El Chico Texas during the period the receipts covered! Probably TMI, but I found those receipts interesting as all get out. Got to see the payouts on several machines, what the ticket value was compared to the prizes etc. (.0045 for the record, with an average ticket payout ratio of 24%) Some of the machines were "hot" with payouts set to 80% for those that have ever had a sneaking suspicion that some machines are paying out more than others.