So I started another campaign earlier today to pass the time at work between EMS calls. I was given the USS Plunger (not wild about the name), and started out on my first patrol. I was sent to the Bandi straight north of manila to patrol for enemy shipping and found a couple of merchants. Deck watch called the contact out, and upon diving to periscope depth, my sonarman wasn't picking anything up.

Thinking that it was just an inexperienced crew member, I threw him to the side and took over the hydrophone station myself. I found to my surprise that the hydrophones weren't working! I knew that the contacts were 034 deg starboard of my bow, but couldn't hear anything.
I continued on, using frequent sweeps with the periscope until I was within range and sent those jap merchants to the deep with the first taking two fish, and the second exploding after one.
Upon returning to manila to complete my patrol, I found that the hydrophone slot on my boat was empty!
Anyone else have this happen on the first patrol?