Inside the mausoleum, we found that there had been considerable snow build-up. This may be a contributing factor to the failed join (and that was precisely what it turned out to be). Here are some photographs of the situation as we found it and the problem cable.
Snow of the cables in the mausoleum. (Photo: D. McKay-Bukowski)
The culprit. A loose ground connection, possibly caused by a misseated o-ring. (Photo: D. McKay-Bukowski)