Hive was bought off a guy last season. Not sure on how old the queen is. I over wintered them in two deeps and fed them all summer into the fall. There just does not seem like there is many bees in there un like the other two hives.
okay, hive purchased last season, unsure of the age of the queen, fed all summer into fall and overwintered, that's a start.and tell how you are doing things... like have you been feeding... how often have you been doing inspections... that kind of thing.
thankswillbrood pattern, start with that. It may be something as simple as the queen is winding down in her career, in which case the bees will replace her, or you may wish to do so by purchasing one. If the brood pattern is good, look at something else. Mite count, any idea how heavy the mite load is on this hive? Uncap a few drone cells in various spots, any mites on the white drone pupae? Is there something that is preventing the queen from access to empty comb to lay in, a pollen barrier (tec term) so to speak?
in general 3 primary reasons for a weak hive (one, a combination, or all of the below):do tell us what you see...
at this point I would suspect a failing queen (no real evidence but just a guess)... when you do the inspection pay close attention to what kind of pattern the current queen is laying.
during the inspection if you sense the hive is very weak adding a frame of brood gives them enough of a boost so they can survive a bit longer until some remedy is decided upon.