After further study, observe the good news from Turn 20!
My StuH42's second shot lands square in between Tiger's two T-34's. Each of them had fired their main gun earlier in the turn while killing my tank hunter, so I know their guns were functional at the start of Turn 20. But this 105mm shell and a later one must have damaged both T-34s' guns !! They never fired again, despite one of them having red-line target on one of my squads.
Observe that at the 0:35 mark, the T-34 draws a bead on my advancing squad.
But he loses target lock at 0:47 despite still having LOS, and never fires. The second 105mm shell can be seen exploding next to the stationary T-34 in the frame at 0:47.