Stubborn NOID phal refuses to bloom

[ZygoSF]

I know what you're thinking - yet another case of not enough light, or a lack of exposure to colder night temperatures for a week or two, or not switching to a phosphorous heavy fertilizer in the fall/winter. But I've tried it all, and this miniature phal just refuses to bloom.

The orchid in question is on an east facing windowsill with good morning light. I got it about 2 years ago, while it had the most beautiful orange blooms, but it hasn't bloomed for me since. I repotted it about a year ago in a mix of clay pellets, bark, sponge rock, and a bit of sphagnum. Lots of growing roots and leaves, though some of the roots may have a bit of fertilizer burn. I've been fertilizing every other week, weakly. The past few months I switched to a blooming fertilizer, and did expose it to some colder temperatures at night (mid 70's during day, low 60's at night) for 10 days or so when we had a cold spell). I have 6 other phals in various stages of spike/bloom, but this one refuses to put out a spike and is driving me nuts!

Anyone have any last-resort treatment for really stubborn phals?