William, thanks for the good information and photos. I have 2 sets of the dps1200's still working thankfully. I found a post on an RC forum about the used PSUs in general. Paraphrased, "they're all used, and were replaced because they don't meet ripple current specifications. They work well as long as not really loaded. The problem is the output capacitors are going bad. if you stay under 40% load current, you will be OK. As you start to go up in load, the ripple increases, and your charger isn't going to like it. If you need to run at a high current, add more caps on the output. Just make sure they have a low ESR." Of course that quote doesn't speak directly to PSU death, but harm to the charger. But they are all well used.
If the above is true, it make some sense to use 24v supplies, two in series, instead of 12V where extra amperage load is used in the step up. And when convenient, to limit the load. Six 6s packs on a parallel board at 5 amps each is still in a reasonable range.