The article on MG lists all of the possible symptoms. When a bird has bubbles in an eye and has conjunctivitis (pinkeye,) they may not have any other symptoms, but they can still have MG. What you need to know about any respiratory infection in even one bird in your flock, is that the others can then also become infected. They may not show symptoms right away, but when there is stress, such as during molt or extreme cold, then symptoms may show up. You can get some testing to confirm, or just treat symptoms. But once you have a respiratory illness, you should never rehome birds. Most people close their flocks, because until all birds are gone, any new bird could get sick from carriers.