Re: your TC dropping to 1, if you're using TDWs New UIs Mod, there are a series of buttons at the top right that control what events drop you to TC1. They all have tooltips, so hover your mouse over them for a few seconds to see what they do.
Not sure about your possible torpedo drift though. One thing to bear in mind about the SH5 TDC - to use the manual input method (either via TDWs extra UI dials or the stock SH5 manual input), you must
lock the target and keep it locked (or not lock it at all).
If you lock a target with the spacebar, then hit spacebar again to unlock, your TDC settings will auto-switch to the exact settings needed to hit the ship (at its current speed/course/aob etc). Using this method you can literally hit space, hit it again, and then aim using the periscope at the target ship and fire (with open tubes) and hit every time, even at extreme range. This is handy if you're lazy -
but if you unlock after inputting manual settings, your inputs will change - this may be skewing your shots.
Or it could of course be something else! Hope this helps
