I've already tried mine, and no issues. But I did a new career, so later today, I'll do similar and apply the mod after going out, and see what happens.
Edit 1530 hours: I have managed to get myself sunk three times in a row now... I've run up the West coast from Manila and tried to intercept the invasion fleet, and I've struck out all three times... The first try wasn't really close, but I did get to within 2800 yards of the middle of the Troop Transports and shot a four torpedo spead. All missed. Three DD came over to see me, and sank me with their first pass. I mean to tell you, dropped a can not only right above me, but right on me, and 210 foot, below the thermal layer... 2nd time, I was a little further East, and let the DD drive right over the top of me, while I was on silent running and below the thermal. Came up to PD, shot another four torpedo spread with almost a 90 degree AOB, this time from 1200 yards from one Transport, and 800 yards from the 2nd... All missed. "Say whuh?" you say! I know, I know... how?? Picked up their skirts and went beneath them, I guess. But they're Mark 10s... Anyway, just about the time #4 was leaving the tube, we took damage from a DD ramming us, taking the periscopes with him and causing massive quantities of flooding... then the boom boom came, and we never made it out of there in 30 minutes of trying... The third try, I don't really want to talk too much about...
... suffice to say, a night surface attack doesn't work so well in GFO... I'm just going to have to take my time on the approaches. I'll post back when I can actually hit something with a torpedo.