Eyesight has returned after surgery and I'm still having trouble with the power.
Here is the wiring diagram from Doepfer (link).
The problem is that the -12v light comes on but the +12v light does not. Today I tried swapping a power unit from a small, empty case (which had two lights on) to the Rack and the situation stayed the same - one light on the Rack, 2 in the case. I used the same power cord and concluded that the problem must be the three inches of wiring from the XLR socket to the Doepfer unit, but that seems to be ok.
The quest continues.
I might install the Livewire Collection in one of the old cases.