We've swapped out both the DSC and 9403 (given time constraints, we're not taking any risks - we'll assess failure points post-ship) and the issue seems to have desisted (although whether the issue had been persisting with the DSC in question is in itself debatable).
We've also opened the DSC in question, but there is no noticeable damage to it. Here it is:
If you'd like, we could send it to you so you could take a look at it.