Well, I introduced eggs into the hive in question a while ago and got one queen cell, but no sign of the queen (i.e. brood) for a long time until a couple of days when a quick inspection revealed a couple of patches of drone brood. I feared the worst, but in hindsight I should not have fretted so much since the drone brood patterns were tight. Anyway, today, I found worker brood so all is well. Thanks to all who responded. Really good ideas. Thanks!