Hello and thanks for the responses. This first pic is of the sick Zygopedalum, before I repotted it.
Can I get away with 2 photos in one post? Anyway, these are 2 of my other orchids, and they seem OK to me. The flowers on the one on the right seem to be at the end of their lives, but the plant itself seems healthy enough. Sorry about the rather cluttered photo - I didn't really think about the composition, just pointed and clicked!