Just give them time...Arms don't like to be moved a whole lot and zoas don't like being touched by bare hands anyhow IMO. I've cut down on a lot of problems I used to have with my zoas since I only handle them wearing latex gloves now. Sound weird but it's been my experience. As for looking for pests, that's great advice. Zoa eating nudibrances turn the color of the zoa they are eating so you really can't see them. It's easier if you look for them under actinic lighting with at least a 10X magnifying glass...higher if you can get it. Look especially well between the polyps and near the skirts. If you see a "bump" or imperfection of any type on the stem but it looks to be part of the zoa, there's a good chance it's a nudi. Just use a pair of very pointy tweezers to see if it moves or can be peeled off, you can also gently scrape at it wih a exacto knife with a fine blade. Just don't gouge the polyp. Good luck.