If it has any good roots don't cut them off. You could always give the S/H method a try. Oncidium types (except Tolumnia and Onc. Twinkle) seem to love it. I had one that was on deaths door and came back with re-plumped bulbs and great growth. It flowered for me this year for the first time since I nearly killed it 3 years ago and was down to 2 bulbs. Now it is in an 6.5" pot and filling in nicely.
