The problem could be the heat sinks but it seems that bitmain acknowledged this problem with the s17 series and supposedly fixed the issue on the S19.
I do agree, after a second thought, I just remembered that the S19 have large heatsinks that cover more than one chip and it's tightened with some screws, so it's unlikely. but still, one bad chip can cause a mess in these hash boards, so I would still do the board by board troubleshooting if they miner still acts weird even after you move it to a new location.