Ask-a-Dave's-Gardener: Help! Zebra Cactus won't grow roots and is withering..., 2 by niknac

niknac wrote:
I really need help with my dying little zebra cactus. I have tried many things, and I don't know what else to do, but it continues to get worse. I don't want it to die!

It all started back in December or January when I noticed some of its lower "leaves" were turning yellow, drying up, and dying/falling off. I learned that the container I bought it in didn't drain and was not the right type of soil. When I pulled it out, the roots all fell off, so I trimmed in back and stuck it in a new pot with more suitable "soil." Through the advice of others, I did not water it because it did not have roots. They told me it would grow roots, THEN I could start watering it. Well, 2 or 3 months later, it still has no roots (see pictures).

I was then told to try giving it tiny amounts of water to encourage root growth. I've tried that for about a month with still no roots growing. It seems to be slowly growing new "leaves" from the center, but the outer ones are turning brownish-yellow, and the rest of it is a dark, redish green. I have it on a south-facing window sill for light (and that's the best I can do as I live in an apartment with only one wall of windows). I have no idea what else to try or to do to save it. Any advice would be appreciated.