Dend. Spectabile and Miva Abracadabra issues.

[Syrinth]

Ok so two problems with my dendrobiums that I'm looking for answers for.

1) My spectabile haven't bloomed, ever. I have two, they were in bloom when I got them, but now no matter what I try, they won't bloom. They keep putting forth new canes which are getting bigger and more unruly each time, but nothing. One of them is even making two canes at once now!

I've been told to give them more light, but I've given as much as I feel I can risk. One of the canes even turned black as seen in the picture. Should I ease off the amount of light they get? South facing window.

2) Meanwhile, my Miva Abracadabra used to be fine. Flowered beautifully and frequently, but the canes were getting smaller and smaller. Now, it keeps making canes but they suddenly shrivel away into nothing as shown. The leaves are also kind of mottled and even dry in some places. I don't think they've been getting too much light. They were under a grow lamp when the problems started, and not directly under either.

I try to water it every second day or so, it seems to dry out fast. As far as I can tell, the roots are still fine, healthy looking ones are sticking out of the bottom.

3) I have another dend, ([pee wee x zip] X Victorian Flare) SVO Intense X Den. Zip Jack McMillen which isn't doing too well either. It's canes over the past dew months have been... withering from the top down? One of them went all the way and got hollowed out. It has three new growths coming up and I'm eager to not screw it up. Any advice?

I took a look at the roots and they didn't look great... that being said, I have a hard time telling with Dendrobium roots.I think it's possible that I may have been overwatering it but I'm not sure how to tell. I cut off a few that look particularly dead and repotted it in sphag with some bark, like it had been in previously, although I basically just put a bit of mix at the bottom, then some sphag and bark at the top since the root ball took up most of the pot.

Any help for anything would be great