1) Go through the bulk (i.e. a lot, not just one or 3 packs) of modules, load tests them, rank them, discard failed which do not meet threshold and compile working pack from similarly performing modules. That is the process I suggest to use and is in use by those who deployed my Complex in their workshop
2) Use the core (that to include wiring, relays, connectors, etc) and install brand new genuine modules from the manufacturer. That is the process used by whoever is authorized to work with and have access to new genuine modules.
On the 30kwh Leafs at least, the degradation seems to be uniform across the cells. Gazley Nissan in Wellington did a test of my rapidly degrading battery and found no bad cells, but capacity is still down. So it seems to be a problem with the chemistry of the cells. Option 2 seems to be the only one in this case.